Process for the preparation of aldehydes and ketones

ABSTRACT

A process for the preparation of vinyl, alkynyl or aryl aldehydes or vinyl, alkynyl or aryl ketones includes reacting vinyl-, alkynyl- and aryl- and -methylene compounds with the aid of a mediator and an oxidant, wherein the mediator is selected from the group of the aliphatic, heterocyclic or aromatic NO or NOH containing compounds.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for the preparation of aldehydes and ketones

2. The Prior Art

Aldehydes and ketones are widely used in organic chemistry. For example, they are important precursors in the synthesis of heterocycles, or perfumes and dyestuffs.

A variety of processes are known for the preparation of aldehydes and ketones. For example, the formyl and the acyl group are successfully introduced directly into aromatic systems via electrophilic substitution reactions, which, however, are limited by the substitution rules. Aromatic ketones can also be synthesized via organometallic reactions. A disadvantage includes the necessity of using an anhydrous reaction medium. Another disadvantage is the use of toxic chemicals such as phosphorus oxychloride, carbon monoxide, zinc cyanide, mercury organyls and cadmium organyls.

Aldehydes and ketones may also be synthesized via oxidation reactions. An overview is given in the literature reviewed in Houben-Weyl, Vol. E3, p. 230 et seq., 1983, and Vol. 7/2a, p. 688 et seq. Customary oxidants are selenium dioxide, chromium trioxide, cerium(IV) ammonium nitrate in perchloric acid/nitric acid or manganese dioxide in concentrated sulfuric acid, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or iodine in DMSO. These oxidants, however, are also not very suitable for larger-scale syntheses due to their toxicity, the high costs or difficult handling. Moreover, most syntheses are complicated and yield the desired aldehyde only in moderate yield. In accordance with Org. Synth. Coll. Vol. IV, 1961, p. 31, 4-aminobenzaldehyde can be synthesized from nitrotoluene with the aid of polysulfide. Purification of the reaction product, which has a tendency to polymerize, is difficult and must be carried out rapidly, so that this process is unsuitable for larger amounts of substance.

When carrying out the oxidation with oxygen with addition of catalysts, not only are the desired aldehydes formed, but in most cases also the corresponding carboxylic acids (see Houben-Weyl, Vol. E3, p. 234 et seq., 1983). If this process is carried out with addition of N-hydroxyphthalimide and Co(II) or Co(III) compounds, even the starting material is fully oxidized to give the carboxylic acid (Ishii et al., J. Org. Chem. 1996, 61, 4520). Aromatic ketones are formed from alkylbenzenes with the aid of N-hydroxyphthalimide and acetaldehyde/oxygen in nonaqueous medium (Einhorn et al. in Chem. Commun. 1997, 447). The formation of aromatic aldehydes from the corresponding methyl aromatics with the aid of the enzyme laccase and ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) was described by Potthast in J. Org. Chem. 1995, 60, 4320. However, it was impossible to reproduce these results in independent experiments. Moreover, the laccase mentioned in the publication, by Mercian, which has an activity of 1.1×10⁴ (IU/ml, based on the conversion of 4-hydroxymandelic acid as substrate), is not available. When attempting to reproduce the results, an available product, namely Mercian laccase with an activity of approx. 95 IU/ml, was employed at 100-fold concentration. A difficulty is that such high amounts of enzyme would completely exclude an applicability of the method for preparative purposes. Under these conditions, not even traces of an oxidation of 4-nitrotoluene was observed. When 3,4-dimethoxytoluene was used in the conversion, only 0.3% of 3,4-dimethoxybenzaldehyde were detected. Synthetic methods using ABTS are generally limited by the price of the compound, which is high.

There is therefore a demand for an inexpensive process which allows even sensitive aldehydes to be synthesized on a large scale. In particular, there is a need for a process in which water can be used as reaction medium.

SUMMARY OF THE INVENTION

The present invention relates to a process for the preparation of vinyl, alkynyl, aryl or heteroaryl aldehydes or vinyl, alkynyl, aryl or heteroaryl ketones from vinyl-, alkynyl-, aryl- and heteroarylmethyl and -methylene compounds with the aid of a mediator and an oxidant, wherein the mediator is selected from the group of the aliphatic, heterocyclic or aromatic NO, NOH or ##STR1## containing compounds.

The vinyl, alkynyl, aryl and heteroaryl aldehydes and vinyl, alkynyl, aryl and heteroaryl ketones are preferably compounds of the formula 1, and the vinyl-, alkynyl-, aryl- and heteroarylmethyl and -methylene compounds are preferably compounds of the formula 2 ##STR2## where Y¹ and Y² can be identical or different and are radicals having up to 20 C atoms and up to 6 rings and at least one of the radicals Y¹ or Y² is vinyl, alkynyl, aryl or heteroaryl, and Y¹ and Y² may also be part of a ring system.

Y¹ is preferably an aromatic or heteroaromatic ring or ring system having up to 6 rings and up to 20 C atoms, whose ring members can be replaced by O, S or N atoms, or an anthraquinonyl radical, it being possible for the aromatic or heteroaromatic radical Y¹ to be mono- to hexasubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₁₂ -alkyl radical, it being possible for adjacent alkyl groups to form a 5-, 6- or 7-membered ring via a methylene group, or a linear or branched C₁ -C₁₂ -oxyalkyl or thioalkyl radical, it being possible for adjacent substituents to form a 5-, 6- or 7-membered ring via a methylene group, a H₂ N-- or a linear or branched C₁ -C₁₂ --N-alkylamino, a linear or branched C₁ -C₁₂ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₁₂ --OCO--, C₁ -C₁₂ --COO--, C₁ -C₁₂ --CO--, C₁ -C₁₂ --NHCO--, C₁ -C₁₂ --NHCONH--, (C₁ -C₁₂)₂ NCO--, C₁ -C₁₂ --CONH-- group, or a linear or branched C₁ -C₁₂ --OSO₂ --, C₁ -C₁₂ --NH--SO₂ --, or (C₁ -C₁₂)₂ N--SO₂ -- group, or a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group whose phenyl radicals can be mono- to pentasubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₁₂ -alkyl radical, it being possible for adjacent alkyl groups to form a 5-, 6- or 7-membered ring via a methylene group, or of a linear or branched C₁ -C₁₂ -oxyalkyl or thioalkyl radical, it being possible for adjacent substituents to form a 5-, 6- or 7-membered ring via a methylene group, a H₂ N-- or a linear or branched C₁ -C₁₂ --N-alkylamino, a linear or branched C₁ -C₁₂ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₁₂ --OCO--, C₁ -C₁₂ --COO--, C₁ -C₁₂ --CO--, C₁ -C₁₂ --NHCO--, C_(1-C) ₁₂ --NHCONH--, (C₁ -C₁₂)₂ NCO--, C₁ -C₁₂ --CONH--, or of a linear or branched C₁ -C₁₂ --OSO₂ --, C₁ -C₁₂ --NH--SO₂ -- or (C_(1-C) ₁₂)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group or an optionally mono- to trisubstituted vinyl radical or optionally substituted ethynyl radical, in which the substituents can be identical or different and have the meaning of hydrogen, linear, branched or cyclic C₁ -C₁₂ -alkyl radical where one or more methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₁₂ --N-alkylamine radical, or in which the vinyl group forms part of a ring or ring system, and Y² is hydrogen, linear, branched or cyclic C₁ -C₁₂ -alkyl radical where one or more methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₁₂ --N-alkylamine radical, or an aromatic or heteroaromatic ring or ring system having up to 6 rings and up to 20 C atoms, whose ring members can be replaced by O, S or N atoms, or anthraquinonyl radical, or an optionally mono- to trisubstituted vinyl radical or optionally substituted ethynyl radical, in which the substituents can be identical or different and have the meaning of hydrogen, linear, branched or cyclic C₁ -C₁₂ -alkyl radical where one or more methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₁₂ --N-alkylamine radical, or in which the vinyl group forms part of a ring or ring system.

Equally preferred are compounds in which the radicals Y¹ and Y² are linked via a methylene group or an ether group or via an amino group which is optionally substituted by a linear, branched or cyclic C₁ -C₁₂ -alkyl radical.

Especially preferably, Y¹ is a 5-, 6- or 7-membered aromatic or heteroaromatic ring which can be fused to one or two further aromatic rings and where one to four C atoms can be replaced by O, S or N atoms, or an anthraquinonyl radical, it being possible for y¹ to be mono- to tetrasubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₆ -alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or a linear or branched C₁ -C₆ -oxyalkyl or -thioalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, of a H₂ N--, or a linear or branched C₁ -C₆ --N-alkylamino, a linear or branched C₁ -C₃ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₆ --OCO--, C₁ -C₆ --COO--, C₁ -C₆ --CO--, C₁ -C₆ --NHCO--, C₁ -C₆ --NHCONH--, (C₁ -C₆)₂ NCO--, C₁ -C₆ --CONH--, or of a linear or branched C₁ -C₆ --OSO₂ --, C₁ -C₆ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group,

it being possible for the phenyl radicals to be mono- to trisubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₆ -alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or a linear or branched C₁ -C₆ -oxyalkyl or -thioalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, of a H₂ N--, or a linear or branched C₁ -C₆ --N-alkylamino, a linear or branched C₁ -C₃ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₆ --OCO--, C₁ -C₆ --COO--, C₁ -C₆ --CO--, C₁ -C₆ --NHCO--, C₁ -C₆ --NHCONH--, (C₁ -C₆)₂ NCO--, C₁ -C₆ --CONH--, or of a linear or branched C₁ -C₆ --OSO₂ --, C₁ -C₆ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group, or

an optionally mono- to trisubstituted vinyl radical or optionally substituted ethynyl radical, it being possible for the substituents to be identical or different and to be hydrogen or linear, branched, or cyclic C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by --CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system, and

Y² is hydrogen or linear, branched or cyclic C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by --CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or a 5-, 6- or 7-membered aromatic or heteroaromatic ring which can be fused to one or two further aromatic rings and where one to four C atoms can be replaced by O, S or N atoms, or an anthraquinonyl radical, or an optionally mono- to trisubstituted vinyl radical, or an optionally substituted ethynyl radical, it being possible for the substituents to be identical or different and to be hydrogen or linear, branched, or cyclic C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by --CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system.

Equally especially preferred are compounds where the radicals Y¹ and Y² are linked via a methylene group or an ether group or via an amino group which is optionally substituted by a linear, branched or cyclic C₁ -C₆ -alkyl radical.

Very especially preferably, Y¹ is phenyl, naphthyl, anthryl, phenanthryl, azulenyl, anthraquinonyl, furyl, pyrrolyl, thienyl, benzofuranyl, isobenzofuranyl, benzothiyl, isobenzothienyl, indolyl, isoindolyl, indolizinyl, pyrazolyl, imidazolyl, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, indazolyl, carbazolyl, benzotriazolyl, purinyl, pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, quinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, cinnolinyl, phenanthridinyl, acridinyl, 1,10-phenanthrolinyl, phenazinyl, phenothiazinyl, phenoxazinyl, it being possible for Y¹ to be mono- to trisubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear C₁ -C₆ -alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or of a linear C₁ -C₆ -oxyalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, a H₂ N--, or a linear C₁ -C₆ --N-alkylamino, a linear C₁ -C₃ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear C₁ -C₄ --OCO--, C₁ -C₄ --COO--, C₁ -C₄ --CO--, C₁ -C₄ --NHCO--, (C₁ -C₄)₂ NCO--, C₁ -C₄ --CONH--, C₁ -C₄ --NHCONH--, or C₁ -C₄ --OSO₂ --, C₁ -C₄ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group, it being possible for the phenyl radicals to be mono- to trisubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear C₁ -C₆ alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or of a linear C₁ -C₆ -oxyalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, a H₂ N--, or a linear C₁ -C₆ --N-alkylamino, a linear C₁ -C₃ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear C₁ -C₄ --OCO--, C₁ -C₄ --COO--, C₁ -C₄ --CO--, C₁ -C₄ --NHCO--, (C_(1-C) ₄)₂ NCO--, C_(1-C) ₄ --CONH--, C₁ -C₄ --NHCONH--, or C₁ -C₄ --OSO₂ --, C₁ -C₄ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group or an optionally mono- to trisubstituted vinyl radical, or optionally substituted ethynyl radical, in which the substituents can be identical or different and are hydrogen or linear C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system, and Y² is hydrogen or a linear C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or is phenyl, naphthyl, anthryl, phenanthryl, azulenyl, anthraquinonyl, furyl, pyrrolyl, thienyl, benzofuranyl, isobenzofuranyl, benzothiyl, isobenzothienyl, indolyl, isoindolyl, indolizinyl, pyrazolyl, imidazolyl, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, indazolyl, carbazolyl, benzotriazolyl, purinyl, pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, quinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, cinnolinyl, phenanthridinyl, acridinyl, 1,10-phenanthrolinyl, phenazinyl, phenothiazinyl, phenoxazinyl, or an optionally mono- to trisubstituted vinyl radical, or optionally substituted ethynyl radical, in which the substituents can be identical or different and are hydrogen or linear C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system.

Examples of such compounds are toluene, ethylbenzene, propylbenzene, ortho-, meta- and para-xylene, 3,4-dimethoxytoluene, 4-methylaniline, diphenylmethane, propene, 2-butene, 1-octene and 3-phenyl-1-propyne.

Equally very especially preferred are compounds in which the radicals Y¹ and Y² are linked via a methylene group or an ether group or via an amino group which is optionally substituted by a methyl, ethyl, n- or iso-propyl radical, the linkage resulting in 5- or 6-membered rings.

Examples are cyclohexene, indane, indene, 1,2,3,4-tetrahydronaphthalene, 6-methoxy-1,2,3,4-tetrahydronaphthalene, 9,10-dihydrophenanthrene, 3,4-dihydro-2H-pyrane, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroisoquinoline.

The mediator used is preferably at least one compound selected from the group of the aliphatic, cycloaliphatic, heterocyclic or aromatic compounds which contains at least one N-hydroxyl, oxime, nitroso, nitroxide or N-oxide function.

Examples of such compounds are the compounds of the formula I, II, III or IV, mentioned below, the compounds of the formulae II, III and IV being preferred and the compounds of the formulae III and IV being especially preferred.

Compounds of the general formula I are: ##STR3## where X is one of the following groups: (--N═N--), (--N═CR⁴ --)_(p), (--CR⁵ ═CR⁶)_(p) ##STR4## and p equals 1 or 2, it is being possible for the radicals R¹ to R⁶ to be identical or different and independently of one another to represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl, and the salts and esters thereof, amino, nitro, C₁ -C₆ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, sulfono, esters and salts thereof, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters, and it furthermore being possible for the amino, carbamoyl and sulfamoyl groups of the radicals R¹ to R⁶ to be unsubstituted or to be mono- or disubstituted by hydroxyl, C₁ -C₃ -alkyl or C₁ -C₃ -alkoxy,

and it being possible for the radicals R² and R³ to form a joint group --A--, where --A-- represents one of the following groups:

(--CR⁷ ═CR⁸ --CR⁹ ═CR¹⁰ --) or (--CR¹⁰ ═CR⁹ --CR⁸ ═CR⁷ --).

The radicals R⁷ to R¹⁰ can be identical or different and independently of one another can represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl and the salts and esters thereof, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl sulfono, esters and salts thereof, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters, and it furthermore being possible for the amino, carbamoyl and sulfamoyl groups of the radicals R⁷ to R¹⁰ to be unsubstituted or to be mono- or disubstituted by hydroxyl, C₁ -C₃ -alkyl or C₁ -C₃ -alkoxy, and it being possible for the C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl or aryl groups of the radicals R⁷ to R¹⁰ to be unsubstituted or furthermore to be mono- or polysubstituted by the radical R¹¹, and it being possible for the radical R¹¹ to represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl and their salts and esters, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, aryl, and their esters and salts, and it being possible for the carbamoyl, sulfamoyl and amino groups of the radical R¹¹ to be unsubstituted or furthermore to be mono- or disubstituted by the radical R¹², and it being possible for the radical R¹ 2 to represent one of the following groups: hydrogen, hydroxyl, formyl, carboxyl and their salts and esters, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl or aryl.

Examples of the abovementioned compounds are:

1-hydroxy-1,2,3-triazole-4,5-dicarboxylic acid

1-phenyl-1H-1,2,3-triazole-3-oxide

5-chloro-1-phenyl -1H-1,2,3-triazole-3-oxide

5-methyl-1-phenyl-1H-1,2,3-triazole-3-oxide

4-(2,2-dimethylpropanoyl) -1-hydroxy-1H-1,2,3-triazole

4-hydroxy-2-phenyl-2H-1,2,3-triazole-1-oxide

2,4,5-triphenyl-2H-1,2,3-triazole-1-oxide

1-benzyl-1H-1,2,3-triazole-3-oxide

1-benzyl-4-chloro-1H-1,2,3-triazole-3-oxide

1-benzyl-4-bromo-1H-1,2,3-triazole-3-oxide

1-benzyl-4-methoxy-1H-1,2,3-triazole-3-oxide

Compounds of the general formula II are: ##STR5## where X is one of the following groups: (--N═N--), (--N═CR⁴ --)_(p), (--CR⁴ ═N--)_(p), (--CR⁵ ═CR⁶)_(p) ##STR6## and p equals 1 or 2.

The radicals R¹ and R⁴ to R¹⁰ can be identical or different and independently of one another can represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl and the salts and esters thereof, amnino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, aryl, sulfono, esters and salts thereof, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters, and it furthermore being possible for the amino, carbamoyl and sulfamoyl groups of the radicals R¹ and R⁴ to R¹⁰ to be unsubstituted or to be mono- or disubstituted by hydroxyl, C₁ -C₃ -alkyl or C₁ -C₃ -alkoxy, and

it being possible for the C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, aryl and aryl-C₁ -C₆ -alkyl groups of the radicals R¹ and R⁴ to R¹⁰ to be unsubstituted or furthermore to be mono- or polysubstituted by the radical R¹², and it being possible for the radical R¹² to represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl and their salts and esters, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, aryl, sulfono, sulfeno, sulfino and their esters and salts,

and it being possible for the carbamoyl, sulfamoyl and amino groups of the radical R¹² to be unsubstituted or furthermore to be mono- or disubstituted by the radical R¹³, and it being possible for the radical R¹³ to represent one of the following groups: hydrogen, hydroxyl, formyl, carboxyl and their salts and esters, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, aryl.

Examples of the abovementioned compounds are:

1-hydroxybenzimidazoles

1-hydroxybenzimidazole-2-carboxylic acid

1-hydroxybenzimidazole

2-methyl-1-hydroxybenzimidazole

2-phenyl-1-hydroxybenzimidazole

1-hydroxyindoles

2-phenyl-1-hydroxyindole

Substances of the general formula III are: ##STR7## where X is one of the following groups: (--N═N--), (--N═CR⁴ --)_(m), (--CR⁴ ═N--)_(m), (--CR⁵ ═CR⁶ --)_(m) ##STR8## and m equals 1 or 2.

What has been said above for the radicals R⁷ to R¹⁰ and R⁴ to R⁶ also applies here.

R¹⁴ can be: hydrogen, C₁ -C₁₀ -alkyl or C₁ -C₁₀ -alkyl-carbonyl whose C₁ -C₁₀ -alkyl and C₁ -C₁₀ -alkylcarbonyl can be unsubstituted or mono- or polysubstituted by a radical R¹⁵, it being possible for R¹⁵ to represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl and salts and esters thereof, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, sulfono, their esters and salts, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters, it being possible for the amino, carbamoyl and sulfamoyl groups of the radical R¹⁵ furthermore to be unsubstituted or mono- or disubstituted by hydroxyl, C₁ -C₃ -alkyl or C₁ -C₃ -alkoxy.

Particularly preferred amongst the substances of the formula III are derivatives of 1-hydroxybenzotriazole and of the tautomeric benzotriazole 1-oxide, and their esters and salts (compounds of the formula IV) ##STR9##

The radicals R⁷ to R¹⁰ can be identical or different and independently of one another represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl and salts and esters thereof, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, sulfono, esters and salts thereof, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters, it furthermore being possible for the amino, carbamoyl and sulfamoyl groups of the radicals R⁷ to R¹⁰ to be unsubstituted or to be mono- or disubstituted by hydroxyl, C₁ -C₃ -alkyl or C₁ -C₃ -alkoxy and it being possible for the C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl and aryl groups of the radicals R⁷ to R¹⁰ to be unsubstituted or furthermore mono- or polysubstituted by the radical R¹⁶, and it being possible for the radical R¹⁶ to represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxyl and their salts and esters, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, aryl, sulfono, sulfeno, sulfino and also their esters and salts, and it being possible for the carbamoyl, sulfamoyl and amino groups of the radical R¹⁶ to be unsubstituted or furthermore mono- or disubstituted by the radical R¹⁷, and it being possible for the radical R¹⁷ to represent one of the following groups: hydrogen, hydroxyl, formyl, carboxyl and their salts and esters, amino, nitro, C₁ -C₁₂ -alkyl, C₁ -C₆ -alkyloxy, carbonyl-C₁ -C₆ -alkyl, phenyl, aryl.

Examples of the abovementioned compounds are:

1-H-hydroxybenzotriazoles

1-hydroxybenzotriazole

1-hydroxybenzotriazole, sodium salt.

1-hydroxybenzotriazole, potassium salt

1-hydroxybenzotriazole, lithium salt

1-hydroxybenzotriazole, ammonium salt

1-hydroxybenzotriazole, calcium salt

1-hydroxybenzotriazole, magnesium salt

1-hydroxybenzotriazole-6-sulfonic acid

1-hydroxybenzotriazole-6-sulfonic acid, monosodium salt

1-hydroxybenzotriazole-6-carboxylic acid

1-hydroxybenzotriazole-6-N-phenylcarboxamide

5-ethoxy-6-nitro-1-hydroxybenzotriazole

4-ethyl-7-methyl-6-nitro-1-hydroxybenzotriazole

2,3-bis(4-ethoxyphenyl)-4,6-dinitro-2,3-dihydro-1-hydroxybenzotriazole

2,3-bis(2-bromo-4-methylphenyl)-4,6-dinitro-2,3-dihydro-1-hydroxybenzotriazole

2,3-bis(4-bromophenyl)-4,6-dinitro-2,3-dihydro-1-hydroxy-benzotriazole

2,3-bis(4-carboxyphenyl)-4,6-dinitro-2,3-dihydro-1-hydroxybenzotriazole

4,6-bis(trifluoromethyl)-1-hydroxybenzotriazole

5-bromo-1-hydroxybenzotriazole

6-bromo-1-hydroxybenzotriazole

4-bromo-7-methyl-1-hydroxybenzotriazole

5-bromo-7-methyl-6-nitro-1-hydroxybenzotriazole

4-bromo-6-nitro-1-hydroxybenzotriazole

6-bromo-4-nitro-1-hydroxybenzotriazole

4-chloro-1-hydroxybenzotriazole

5-chloro-1-hydroxybenzotriazole

6-chloro-1-hydroxybenzotriazole

6-chloro-5-isopropyl-1-hydroxybenzotriazole

5-chloro-6-methyl-1-hydroxybenzotriazole

6-chloro-5-methyl-1-hydroxybenzotriazole

4-chloro-7-methyl-6-nitro-1-hydroxybenzotriazole

4-chloro-5-methyl-1-hydroxybenzotriazole

5-chloro-4-methyl-1-hydroxybenzotriazole

4-chloro-6-nitro-1-hydroxybenzotriazole

6-chloro-4-nitro-1-hydroxybenzotriazole

7-chloro-1-hydroxybenzotriazole

6-diacetylamino-1-hydroxybenzotriazole

2,3-dibenzyl-4,6-dinitro-2,3-dihydro-1-hydroxybenzotriazole

4,6-dibromo-1-hydroxybenzotriazole

4,6-dichloro-1-hydroxybenzotriazole

5,6-dichloro-1-hydroxybenzotriazole

4,5-dichloro-1-hydroxybenzotriazole

4,7-dichloro-1-hydroxybenzotriazole

5,7-dichloro-6-nitro-1-hydroxybenzotriazole

5,6-dimethoxy-1-hydroxybenzotriazole

2,3-di-[2]naphthyl-4,6-dinitro-2,3-dihydro-1-hydroxybenzotriazole

4,6-dinitro-1-hydroxybenzotriazole

4,6-dinitro-2,3-diphenyl-2,3-dihydro-1-hydroxybenzotriazole

4,6-dinitro-2,3-di-p-tolyl-2,3-dihydro-1-hydroxybenzotriazole

5-hydrazino-7-methyl-4-nitro-1-hydroxybenzotriazole

5,6-dimethyl-1-hydroxybenzotriazole

4-methyl-1-hydroxybenzotriazole

5-methyl-1-hydroxybenzotriazole

6-methyl-1-hydroxybenzotriazole

5-(1-methylethyl)-1-hydroxybenzotriazole

4-methyl-6-nitro-1-hydroxybenzotriazole

6-methyl-4-nitro-1-hydroxybenzotriazole

5-methoxy-1-hydroxybenzotriazole

6-methoxy-1-hydroxybenzotriazole

7-methyl-6-nitro-1-hydroxybenzotriazole

4-nitro-1-hydroxybenzotriazole

6-nitro-1-hydroxybenzotriazole

6-nitro-4-phenyl-1-hydroxybenzotriazole

5-phenylmnethyl-1-hydroxybenzotriazole

4-trifluoromethyl1-hydroxybenzotriaz ole

5-trifluoromethyl-1-hydroxybenzotriazole

6-trifluoromethyl-1-hydroxybenzotriazole

4,5,6,7-tetrachloro-1-hydroxybenzotriazole

4, 5,6,7-tetrafluoro-1-hydroxybenzotriazole

6-tetrafluoroethyl-1-hydroxybenzotriazole

4,5,6-trichloro-1-hydroxybenzotriazole

4, 6,7-trichloro-1-hydroxybenzotriazole

6-sulfamido-1-hydroxybenzotriazole

6-N,N-diethylsulfamido-1-hydroxybenzotriazole

6-N-methylsulfamido-1-hydroxybenzotriazole

6-(1H-1,2,4-triazol-1-ylmethyl)-1-hydroxybenzotriazole

6-(5,6,7,8-tetrahydroimnidazo[1,5-a]pyridin-5-yl)-1-hydroxybenzotriazole

6-(phenyl-1H-1,2,4-triazol-1-ylmethyl)-1-hydroxybenzotriazole

6-[(5-methyl-1H-imidazo-1-yl) phenylmnethyl]-1-hydroxybenzotriazole

6-[(4-methyl-1H-imidazo-1-yl)phenylmethyl]-1-hydroxybenzotriazole

6-[(2-methyl-1H-imidazo-1-yl)phenylmethyl]-1-hydroxybenzotriazole

6-(1H-imidazol-1-ylphenylmethyl)-1-hydroxybenzotriazole

5-(1H-imidazol-1-ylphenylmethyl)-1-hydroxybenzotriazole

6-[1-(1H-imidazol-1-yl)ethyl]-1-hydroxybenzotriazole monohydrochloride

3H-benzotriazole 1-oxides

3H-benzotriazole 1-oxide

6-acetyl-3H-benzotriazole 1-oxide

5-ethoxy-6-nitro-3H-benzotriazole 1-oxide

4-ethyl-7-methyl-6-nitro-3H-benzotriazole 1-oxide

6-amino-3,5-dimethyl-3H-benzotriazole 1-oxide

6-amino-3-methyl-3H-benzotriazole 1-oxide

5-bromo-3H-benzotriazole 1-oxide

6-bromo-3H-benzotriazole 1-oxide

4-bromo-7-methyl-3H-benzotriazole 1-oxide

5-bromo-4-chloro-6-nitro-3H-benzotriazole 1-oxide

4-bromo-6-nitro-3H-benzotriazole 1-oxide

6-bromo-4-nitro-3H-benzotriazole 1-oxide

5-chloro-3H-benzotriazole 1-oxide

6-chloro-3H-benzotriazole 1-oxide

4-chloro-6-nitro-3H-benzotriazole 1-oxide

4 6-dibromo-3H-benzotriazole 1-oxide

4,6-dibromo-3-methyl-3H-benzotriazole 1-oxide

4,6-dichloro-3H-benzotriazole 1-oxide

4,7-dichloro-3H-benzotriazole 1-oxide

5,6-dichloro-3H-benzotriazole 1-oxide

4,6-dichloro-3-methyl-3H-benzotriazole 1-oxide

5,7-dichloro-6-nitro-3H-benzotriazole 1-oxide

3,6-dimethyl-6-nitro-3H-benzotriazole 1-oxide

3,5-dimethyl-6-nitro-3H-benzotriazole 1-oxide

3-methyl-3H-benzotriazole 1-oxide

5-methyl-3H-benzotriazole 1-oxide

6-methyl-3H-benzotriazole 1-oxide

6-methyl-4-nitro-3H-benzotriazole 1-oxide

7-methyl-6-nitro-3H-benzotriazole 1-oxide

5-chloro-6-nitro-3H-benzotriazole 1-oxide

2H-benzotriazole 1-oxides

2-(4-acetoxyphenyl)-2H-benzotriazole 1-oxide

6-acetylamino-2-phenyl-2H-benzotriazole 1-oxide

2-(4-ethylphenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-(3-aminophenyl)-2H-benzotriazole 1-oxide

2-(4-aminophenyl)-2H-benzotriazole 1-oxide

6-amino-2-phenyl-2H-benzotriazole 1-oxide

5-bromo-4-chloro-6-nitro-2-phenyl-2H-benzotriazole 1-oxide

2-(4-bromophenyl)-2H-benzotriazole 1-oxide

5-bromo-2-phenyl-2H-benzotriazole 1-oxide

6-bromo-2-phenyl-2H-benzotriazole 1-oxide

2-(4-bromophenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-(4-bromophenyl)-6-nitro-2H-benzotriazole 1-oxide

5-chloro-2-(2-chlorophenyl)-2H-benzotriazole 1-oxide

5-chloro-2-(3-chlorophenyl)-2H-benzotriazole 1-oxide

5-chloro-2-(2-chlorophenyl)-2H-benzotriazole 1-oxide

5-chloro-2-(3-chlorophenyl)-2H-benzotriazole 1-oxide

5-chloro-2-(2,4-dibromophenyl)-2H-benzotriazole 1-oxide

5-chloro-2-(2,5-dimethylphenyl)-2H-benzotriazole 1-oxide

5-chloro-2-(4-nitrophenyl)-2H-benzotriazole 1-oxide

5-chloro-6-nitro-2-phenyl-2H-benzotriazole 1-oxide

2-[4-(4-chloro-3-nitrophenylazo)-3-nitrophenyl]-4,6-dinitro-2H-benzotriazole 1-oxide

2-(3-chloro-4-nitrophenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-(4-chloro-3-nitrophenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

4-chloro-6-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

5-chloro-6-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

6-chloro-4-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

2-(2-chlorophenyl)-2H-benzotriazole 1-oxide

2-(3-chlorophenyl)-2H-benzotriazole 1-oxide

2-(4-chlorophenyl)-2H-benzotriazole 1-oxide

5-chloro-2-phenyl-2H-benzotriazole 1-oxide

2-[4-(4-chlorophenylazo)-3-nitrophenyl]-4,6-dinitro-2H-benzotriazole 1-oxide

2-(2-chlorophenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-(3-chlorophenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-(4-chlorophenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-{4-[N'-(3-chlorophenyl)hydrazino]-3-nitrophenyl}-4,6-dinitro-2H-benzotriazole 1-oxide

2-{4-[N'-(4-chlorophenyl)hydrazino]-3-nitrophenyl}-4,6-dinitro-2H-benzotriazole 1-oxide

2-(2-chlorophenyl)-6-methyl-2H-benzotriazole 1-oxide

2-(3-chlorophenyl)-6-methyl-2H-benzotriazole 1-oxide

2-(4-chlorophenyl)-6-methyl-2H-benzotriazole 1-oxide

2-(3-chlorophenyl)-6-nitro-2H-benzotriazole 1-oxide

2-(4-chlorophenyl)-6-nitro-2H-benzotriazole 1-oxide

2-(4-chlorophenyl)-6-picrylazo-2H-benzotriazole 1-oxide

5-chloro-2-(2,4,5-trimethylphenyl)-2H-benzotriazole 1-oxide

4,5-dibromo-6-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

4,5-dichloro-6-nitro-2-phenyl-2H-benzotriazole 1-oxide

4,5-dichloro-6-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

4,7-dichloro-6-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

4,7-dimethyl-6-nitro-2-phenyl-2H-benzotriazole 1-oxide

2-(2,4-dimethylphenyl)-4,6-dinitro-benzotriazole 1-oxide

2-(2,5-dimethylphenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-(2,4-dimethylphenyl)-6-nitro-2H-benzotriazole 1-oxide

2-(2,5-dimethylphenyl)-6-nitro-2H-benzotriazole 1-oxide

4,6-dinitro-2-[3-nitro-4-(N'-phenylhydrazino)phenyl]-2H-benzotriazole 1-oxide

4,6-dinitro-2-[4-nitro-4-(N'-phenylhydrazino)phenyl]-2H-benzotriazole 1-oxide

4,6-dinitro-2-phenyl-2H-benzotriazole 1-oxide

2-(2,4-dinitrophenyl)-4,6-dinitro-2H-benzotriazole 1-oxide

2-(2,4-dinitrophenyl)-6-nitro-2H-benzotriazole 1-oxide

4,6-dinitro-2-o-tolyl-2H-benzotriazole 1-oxide

4,6-dinitro-2-p-tolyl-2H-benzotriazole 1-oxide

4,6-dinitro-2-(2,4,5-trimethylphenyl)-2H-benzotriazole 1-oxide

2-(4-methoxyphenyl)-2H-benzotriazole 1-oxide

2-(4-methoxyphenyl)-6-methyl-2H-benzotriazole 1-oxide

5-methyl-6-nitro-2-m-tolyl-2H-benzotriazole 1-oxide

5-methyl-6-nitro-2-o-tolyl-2H-benzotriazole 1-oxide

5-methyl-6-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

6-methyl-4-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

6-methyl-2-phenyl-2H-benzotriazole 1-oxide

4-methyl-2-m-tolyl-2H-benzotriazole 1-oxide

4-methyl-2-o-tolyl-2H-benzotriazole 1-oxide

4-methyl-2-p-tolyl-2H-benzotriazole 1-oxide

6-methyl-2-m-tolyl-2H-benzotriazole 1-oxide

6-methyl-2-o-tolyl-2H-benzotriazole 1-oxide

6-methyl-2-p-tolyl-2H-benzotriazole 1-oxide

2-[1]naphthyl-4,6-dinitro-2H-benzotriazole 1-oxide

2-[2]naphthyl-4,6-dinitro-2H-benzotriazole 1-oxide

2-[1]naphthyl-6-nitro-2H-benzotriazole 1-oxide

2-[2]naphthyl-6-nitro-2H-benzotriazole 1-oxide

2-(3-nitrophenyl)-2H-benzotriazole 1-oxide

6-nitro-2-phenyl-2H-benzotriazole 1-oxide

4-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

6-nitro-2-o-tolyl-2H-benzotriazole 1-oxide

6-nitro-2-p-tolyl-2H-benzotriazole 1-oxide

6-nitro-2-(2,4,5-trimethylphenyl)-2H-benzotriazole 1-oxide

2-phenyl-2H-benzotriazole 1-oxide

2-o-tolyl-2H-benzotriazole 1-oxide

2-p-tolyl-2H-benzotriazole 1-oxide

The mediator can preferably furthermore be selected amongst the group consisting of cyclic N-hydroxy compounds having at least one optionally substituted five or six-membered ring which contains the structure mentioned in formula V ##STR10## and their salts, ethers or esters, where B and D are identical or different and are O, S or NR¹⁸,

R¹⁸ being hydrogen, hydroxyl, formyl, carbamoyl, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono, phosphonooxy radical, ester or salt of the phosphonooxy radical,

it being possible for carbamoyl, sulfamoyl, amino and phenyl radicals to be unsubstituted or mono- or polysubstituted by a radical R¹⁹ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R¹⁹,

R¹⁹ being identical or different and being a hydroxyl, formyl or carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono or ester or salt of the sulfono radical, sulfamoyl, nitro, amino, phenyl, C₁ -C₅ -alkyl or C₁ -C₅ -alkoxy radical.

The mediator is preferably selected from the group of the compounds of the general formula VI, VII, VIII or IX, ##STR11## where B and D have the meanings which have already been mentioned and the radicals R²⁰ -R³⁵ are identical or different and are a halogen radical, carboxyl radical, salt or ester of a carboxyl radical or have the meanings mentioned for R¹⁸, where R²⁶ and R²⁷, or R²⁸ and R²⁹, respectively, must not simultaneously be a hydroxyl or amino radical, and where, if appropriate, in each case two of the substituents R²⁰ -R²³, R²⁴ -R²⁵, R²⁶ -R²⁹, R³⁰ -R³⁵ can be linked to give a ring --E--, --E-- having one of the following meanings:

(--CH═CH)--_(n), where n=1 to 3, --CH═CH--CH═N-- or ##STR12## and where, if appropriate, the radicals R²⁶ -R²⁹ can also be linked to each other by one or more bridging elements --F--, --F-- being identical or different and having one of the following meanings: --O--, --S, --CH₂ --, --CR³⁶ ═CR³⁷ ; R³⁶ and R³⁷ being identical or different and having the meaning of R²⁰.

Especially preferred as mediators are compounds of the general formulae VI, VII, VIII or IX, where B and D are O or S.

Examples of such compounds are N-hydroxyphthalimide and optionally substituted N-hydroxyphthalimide derivatives, N-hydroxymaleimide and optionally substituted N-hydroxymaleimide derivatives, N-hydroxynaphthalimide and optionally substituted N-hydroxynaphthalimide derivatives, N-hydroxysuccinimide and optionally substituted N-hydroxysuccinimide derivatives, preferably those where the radicals R²⁶ -R²⁹ are linked in the form of polycycles.

Particularly preferred as mediator are N-hydroxyphthalimide, 4-amino-N-hydroxyphthalimide and 3-amino-N-hydroxyphthalimide.

Examples of compounds of the formula VI which are suitable as mediator are:

N-hydroxyphthalimide,

4-amino-N-hydroxyphthalimide,

3-amino-N-hydroxyphthalimide,

N-hydroxybenzene-1,2,4-tricarboximide,

N,N'-dihydroxypyromellitic diimide,

N,N'-dihydroxybenzophenone-3,3',4,4'-tetracarboxylic duimide.

Examples of compounds of the formula VII which are suitable as mediator are:

N-hydroxymaleimide,

N-hydroxy-pyridine-2,3-dicarboximide.

Examples of compounds of the formula VIII which are suitable as mediator are:

N-hydroxysuccinimide,

N-hydroxytartarimide,

N-hydroxy-5-norbornene-2,3-dicarboximide,

exo--N-hydroxy-7-oxabicyclo[2.2.1]-hept-5-ene-2,3-dicarboximide,

N-hydroxy-cis-cyclohexane-1,2-dicarboximide,

N-hydroxy-cis-4-cyclohexene-1,2-dicarboximide.

An example of the compound of the formula IX which is suitable as mediator is:

N-hydroxynaphthalimide-sodium salt.

An example of a compound with a six-membered ring containing the structure mentioned in formula V and suitable as mediator is:

N-hydroxyglutarimide.

The compounds which have been mentioned by way of example are also suitable as mediator in the form of their salts or esters.

Also suitable as mediator are compounds selected from the group of the N-aryl-N-hydroxy-amides.

Amongst these, compounds which are preferably employed as mediators are those of the general formula X, ##STR13## and their salts, ethers or esters, where G is a monovalent homo- or heteroaromatic mono- or binuclear radical and

L is a divalent homo- or heteroaromatic mono- or binuclear radical, and

it being possible for these aromatics to be substituted by one or more identical or different radicals R³⁸ selected from the group consisting of halogen, hydroxyl, formyl, cyano, carbamoyl, carboxyl radical, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono or phosphonooxy radical, ester or salt of the phosphonooxy radical, and it being possible for carbamoyl, sulfamoyl, amino and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R³⁹ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R³⁹,

R³⁹ being identical or different and being hydroxyl, formyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₅ -alkylcarbonyl radical and

it being possible for in each case two radicals R³⁸ or R³⁹ to be linked, in pairs, via a bridge [--CR⁴⁰ R⁴¹ --]_(m) where m equals 0, 1, 2, 3 or 4 and

R⁴⁰ and R⁴¹ are identical or different and are a carboxyl radical, ester or salt of the carboxyl radical, phenyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₅ -alkylcarbonyl radical and it being possible for one or more nonadjacent groups [--CR⁴⁰ R⁴¹ --] to be replaced by oxygen, sulfur or by an imino radical which is optionally substituted by C₁ to C₅ -alkyl radical and it being possible for two adjacent groups [--CR⁴⁰ R⁴¹ --] to be replaced by a group [--CR⁴⁰ ═CR⁴¹ --] and I is a monovalent acid radical, present in amide form, of acids selected from the group consisting of carboxylic acid having up to 20 C atoms, carbonic acid, monoester of carbonic acid or of carbamic acid, sulfonic acid, phosphonic acid, phosphoric acid, monoester of phosphoric acid, diester of phosphoric acid and

K is a divalent acid radical, present in amide form, of acids selected from the group consisting of mono- and dicarboxylic acids having up to 20 C atoms, carbonic acid, sulfonic acid, phosphonic acid, phosphoric acid or monoester of phosphoric acid.

Especially preferred as mediators are compounds of the general formula XIII, XIV, XV, XVI or XVII: ##STR14## and their salts, ethers or esters, where Ar¹ is a monovalent homo- or heteroaromatic mononuclear aryl radical and

Ar² is a divalent homo- or heteroaromatic mononuclear aryl radical,

each of which can be substituted by one or more identical or different radicals R⁴⁴ selected from the group consisting of hydroxyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, nitro, nitroso, amino, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl or carbonyl-C₁ -C₆ -alkyl radical,

it being possible for amino radicals to be unsubstituted or mono- or polysubstituted by a radical R⁴⁵ and it being possible for the C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁴⁵,

R⁴⁵ being identical or different and being hydroxyl, carboxyl radical, ester or salt of the carboxyl radical, sulfono, nitro, amino, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₅ -alkylcarbonyl radical and

it being possible for in each case two radicals R⁴⁴ to be linked, in pairs, via a bridge [--CR⁴⁰ R⁴¹ --]_(m) where m equals 0, 1, 2, 3 or 4 and

R⁴⁰ and R⁴¹ have the meanings which have already been mentioned and one or more nonadjacent groups [--CR⁴⁰ R⁴¹ --] can be replaced by oxygen, sulfur or by an imino radical which is optionally substituted by a C₁ to C₅ -alkyl radical, and two adjacent groups [--CR⁴⁰ R⁴¹ --] can be replaced by a group [--CR⁴⁰ ═CR⁴¹ --],

R⁴² is identical or different monovalent radicals selected from the group consisting of hydrogen, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₁₀ -carbonyl radical, it being possible for phenyl radicals to be unsubstituted or mono- or polysubstituted by a radical R⁴⁶ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy and C₁ -C₁₀ -carbonyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁴⁶,

R⁴⁶ being identical or different and being hydroxyl, formyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, C₁ -C₅ -alkyl or C₁ -C₅ -alkoxy radical and

R⁴³ being divalent radicals selected from the group consisting of ortho-, meta-, para-phenylene, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkylene or C₁ -C₅ -alkylenedioxy radical, it being possible for the phenylene radicals to be unsubstituted or mono- or polysubstituted by a radical R⁴⁶ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl or C₁ -C₅ -alkoxy radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁴⁶,

p being 0 or 1 and

q being an integer from 1 to 3.

Preferably, Ar¹ is a phenyl radical and Ar² an ortho-phenylene radical, it being possible for Ar¹ to be substituted by up to five and for Ar² to be substituted by up to four identical or different radicals selected from the group consisting of C₁ -C₃ -alkyl, C₁ -C₃ -alkylcarbonyl, carboxyl radical, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, hydroxyl, cyano, nitro, nitroso and amino radical, it being possible for amino radicals to be substituted by two different radicals selected from the group consisting of hydroxyl and C₁ -C₃ -alkylcarbonyl.

Preferably, R⁴² is a monovalent radical selected from the group consisting of hydrogen, phenyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy radical, it being possible for the C₁ -C₁₂ -alkyl radicals and the C₁ -C₅ -alkoxy radicals to be saturated or unsaturated, branched or unbranched.

Preferably, R⁴³ is divalent radicals selected from the group consisting of ortho- or para-phenylene, C₁ -C₁₂ -alkylene, C₁ -C₅ -alkylenedioxy radical, it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl and C₁ -C₅ -alkoxy radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical

R⁴⁶ is preferably carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, phenyl or C₁ -C₃ -alkoxy radical.

Examples of compounds which can be employed as mediators are N-hydroxyacetanilide, N-hydroxypivaloylanilide, N-hydroxyacrylanilide, N-hydroxybenzoylanilide, N-hydroxymethylsulfonylanilide, N-hydroxy-N-phenylmethylcarbamate, N-hydroxy-3-oxo-butyrylanilide, N-hydroxy-4-cyanoacetanilide, N-hydroxy-4-methoxyacetanilide, N-hydroxyphenacetin, N-hydroxy-2,3-dimethylacetanilide, N-hydroxy-2-methylacetanilide, N-hydroxy-4-methyl-acetanilide, 1-hydroxy-3,4-dihydroquinolin-(1H)-2-one, N,N'-dihydroxy-N,N'-diacetyl-1,3-phenylenediamine, N,N'-dihydroxysuccinanilide, N,N'-dihydroxymaleianilide, N,N'-dihydroxyoxalanilide, N,N'-dihydroxyphosphoranilide, N-acetoxyacetanilide, N-hydroxymethyloxalylanilide, N-hydroxymaleianilide.

Mediators which are preferably used are N-hydroxyacetanilide, N-hydroxyformanilide, N-hydroxy-N-phenylmethylcarbamate, N-hydroxy-2-methylacetanilide, N-hydroxy-4-methylacetanilide, 1-hydroxy-3,4-dihydroquinolin-(1H)-2-one and N-acetoxyacetanilide.

The mediator can furthermore be selected from the group of the N-alkyl-N-hydroxy-amides.

Mediators which are preferably employed are compounds of the general formula (XVIII) or (XIX) ##STR15## and their salts, ethers or esters, where M is identical or different and is a monovalent linear or branched or cyclic or polycyclic saturated or unsaturated alkyl radical having 1-24 C atoms, and

it being possible for this alkyl radical to be substituted by one or more radicals R⁴⁸, which are identical or different and are selected from the group consisting of hydroxyl, mercapto, formyl, carbamoyl, carboxyl, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, hydroxylamino, phenyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, phospho, phosphono, phosphonooxy radical, ester or salt of the phosphonooxy radical, and

it being possible for carbamoyl, sulfamoyl, amino, hydroxylamino, mercapto and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁴⁸, and it being possible for the C₁ -C₅ -alkoxy and C₁ -C₁₀ -carbonyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁴⁸,

R⁴⁸ being identical or different and being hydroxyl, formyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, benzoyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₅ -alkylcarbonyl radical, and it being possible for methylene groups which are not in the α-position to be replaced by oxygen, sulfur or by an optionally mono-substituted imino radical, and where

N is a monovalent acid radical, present in amide form, of acids selected from the group consisting of aliphatic or mono- or binuclear aromatic or mono- or binuclear hetero-aromatic carboxylic acids having up to 20 C atoms, carbonic acid, monoester of carbonic acid or of carbamic acid, sulfonic acid, phosphonic acid, phosphoric acid, monoester of phosphoric acid, diester of phosphoric acid, and

T is a divalent acid radical, present in amide form, of acids selected from the group consisting of aliphatic, mono- or binuclear aromatic or mono- or binuclear hetero-aromatic dicarboxylic acids having up to 20 C atoms, carbonic acid, sulfonic acid, phosphonic acid, phosphoric acid, monoester of phosphoric acid, and

it being possible for alkyl radicals of the aliphatic acids N and T, present in amide form, to be linear or branched and/or to be saturated or unsaturated in the cycle and/or polycycle and to contain 0-24 carbon atoms and to be unsubstituted or to be mono- or polysubstituted by the radical R⁴⁷ and

it being possible for aryl and heteroaryl radicals of the aromatic or heteroaromatic acids N and T. present in amide form, to be substituted by one or more radicals R⁴⁹ which are identical or different and are selected from the group consisting of hydroxyl, mercapto, formyl, cyano, carbamoyl, carboxyl, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, phospho, phosphono, phosphonooxy radical, ester or salt of the phosphonooxy radical and

it being possible for carbamoyl, sulfamoyl, amino, mercapto and phenyl radicals to be unsubstituted or mono- or polysubstituted by the radical R⁴⁸ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl-C_(l-C) ₅ -alkoxy and C₁ -C₁₀ -carbonyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by the radical R⁴⁸.

Especially preferred as mediators are compounds of the general formula (XX, XXI, XXII or XXIII): ##STR16## and their salts, ethers or esters, where Alk¹ is identical or different and is a monovalent linear or branched or cyclic or polycyclic saturated or unsaturated alkyl radical having 1-10 C atoms,

it being possible for this alkyl radical to be substituted by one or more radicals R⁵⁰ which are identical or different and are selected from the group consisting of hydroxyl, formyl, carbamoyl, carboxyl, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, hydroxylamino, phenyl, C₁ -C₅ -alkoxy or C₁ -C₅ -carbonyl radicals and it being possible for carbamoyl, sulfamoyl, amino, hydroxylamino and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁵¹ and it being possible for the C₁ -C₅ -alkoxy and C₁ -C₁₀ -carbonyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁵¹,

R⁵¹ being identical or different and being hydroxyl, formyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, amino, phenyl, benzoyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₅ -alkylcarbonyl radical and

it being possible for methylene groups which are not in the α-position to be replaced by oxygen, sulfur or by an optionally monosubstituted imino radical and R⁵² being identical or different monovalent radicals selected from the group consisting of hydrogen, phenyl, pyridyl, furyl, pyrrolyl, thienyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₁₀ -alkoxy or C₁ -C₁₀ -carbonyl radical,

it being possible for phenyl, pyridyl, furyl, pyrrolyl and thienyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁷ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy and C₁ -C₁₀ -carbonyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁵³ and

R⁵³ is identical or different and is hydroxyl, formyl, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, amino, phenyl, C₁ -C₅ -alkyl or C₁ -C₅ -alkoxy radical and

R⁵⁴ is divalent radicals selected from the group consisting of phenylene, pyridylene, thienylene, furylene, pyrrolylene, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkylene or C₁ -C₅ -alkylenedioxy radical, it being possible for phenylene, pyridylene, thienylene, furylene and pyrrolylene to be unsubstituted or to be mono- or polysubstituted by a radical R⁵³ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl and C₁ -C₅ -alkoxy radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁵³, p being 0 or 1.

Very especially preferred as mediators are compounds of the general formulae (XX-XXIII), where Alk¹ is identical or different and is a monovalent linear or branched or cyclic saturated or unsaturated alkyl radical having 1-10 C atoms,

it being possible for this alkyl radical to be substituted by one or more radicals R⁵⁰ which are identical or different and are selected from the group consisting of hydroxyl, carbamoyl, carboxyl, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, amino, phenyl, C₁ -C₅ -alkoxy or C₁ -C₅ -carbonyl radicals and

it being possible for carbamoyl, sulfamoyl, amino and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁵¹ and it being possible for the C₁ -C₅ -alkoxy and C₁ -C₁₀ -carbonyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁵¹,

R⁵¹ being identical or different and being hydroxyl, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, amino, phenyl, benzoyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₅ -alkylcarbonyl radical and

R⁵² being identical or different monovalent radicals selected from the group consisting of hydrogen, phenyl, furyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₁₀ -alkoxy or C₁ -C₁₀ -carbonyl radical,

it being possible for phenyl and furyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁵³ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy and C₁ -C₁₀ -carbonyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁵³,

R⁵³ being identical or different and being a carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, phenyl, C₁ -C₅ -alkyl or C₁ -C₅ -alkoxy radical and R⁵⁴ is a divalent radical selected from the group consisting of phenylene, furylene, C₁ -C₁₂ -alkylene and C₁ -C₅ -alkylenedioxy radical, it being possible for phenylene and furanylene to be unsubstituted or to be mono- or polysubstituted by a radical R⁵³ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl and C₁ -C₅ -alkoxy radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁵³,

p being 0 or 1.

Examples of compounds which can be employed as mediators are

N-hydroxy-N-methylbenzamide, N-hydroxy-N-methylbenzene-sulfonamide, N-hydroxy-N-methyl-p-toluenesulfonamide, N-hydroxy-N-methylfuran-2-carboxamide, N-hydroxy-N-methyl-thiophene-2-carboxamide, N,N'-dihydroxy-N,N'-dimethyl-phthalamide, N,N'-dihydroxy-N,N'-dimethylisophthalamide, N,N'-dihydroxy-N,N'-dimethylterephthalamide, N,N'-dihydroxy-N,N'-dimethylbenzene-1,3-disulfonamide, N,N'-dihydroxy-N,N'-dimethylfuran-3,4-dicarboxamide, N-hydroxy-N-tert-butylbenzamide, N-hydroxy-N-tert-butyl-benzenesulfonamide, N-hydroxy-N-tert-butyl-p-toluene-sulfonamide,

N-hydroxy-N-tert-butylfuran-2-carboxamide,

N-hydroxy-N-tert-butylthiophene-2-carboxamide,

N,N'-dihydroxy-N,N'-di-tert-butylphthalamide,

N,N'-dihydroxy-N,N'-di-tert-butylisophthalamide,

N,N'-dihydroxy-N,N'-di-tert-butylterephthalamide,

N,N'-dihydroxy-N,N'-di-tert-butylbenzene-1,3-disulfonamide,

N,N'-dihydroxy-N,N'-di-tert-butylfuran-3,4-dicarboxamide,

N-hydroxy-N-cyclohexylbenzamide, N-hydroxy-N-cyclohexylbenzenesulfonamide,

N-hydroxy-N-cyclohexyl-p-toluenesulfonamide,

N-hydroxy-N-cyclohexylfuran-2-carboxamide,

N-hydroxy-N-cyclohexylthiophene-2-carboxamide,

N,N'-dihydroxy-N,N'-dicyclohexylphthalamide,

N,N'-dihydroxy-N,N'-dicyclohexylisophthalamide,

N,N'-dihydroxy-N,N'-dicyclohexylterephthalamide,

N,N'-dihydroxy-N,N'-dicyclohexylbenzene-1,3-disulfonamide,

N,N'-dihydroxy-N,N'-dicyclohexylfuran-3,4-dicarboxamide,

N-hydroxy-N-isopropylbenzamide, N-hydroxy-N-isopropylbenzenesulfonamide, N-hydroxy-N-isopropyl-p-toluenesulfonamide, N-hydroxy-N-isopropylfuran-2-carboxamide, N-hydroxy-N-isopropylthiophene-2-carboxamide, N,N'-dihydroxy-N,N -diisopropylphthalamide, N,N'-dihydroxy-N,N'-diisopropylisophthala mide, N,N'-dihydroxy-N,N'-diisopropylterephthalainide, N,N'-dihydroxy-N,N'-diisopropylbenzene-1,3-disulfonamide, N,N'-dihydroxy-N,N'-diisopropylfuran-3,4-dicarboxamide, N-hydroxy-N-methylacetamide, N-hydroxy-N-tert-butylacetamide, N-hydroxy-N-isopropylacetamide, N-hydroxy-N-cyclohexylacetamide, N-hydroxy-N-methylpivalamide, N-hydroxy-N-isopropyl-pivalamide, N-hydroxy-N-methylacrylamide, N-hydroxy-N-tert-butylacrylamide, N-hydroxy-N-isopropylacrylamide, N-hydroxy-N-cyclohexylacrylamide, N-hydroxy-N-methylmethanesulfonamide, N-hydroxy-N-isopropylmethanesulfonamide, N-hydroxy-N-isopropylmethylcarbamate, N-hydroxy-N-methyl-3-oxobutyramide, N,N'-dihydroxy-N,N'-dibenzoylethylenediamine, N,N'-dihydroxy-N,N'-dimethylsuccinamide,

N,N'-dihydroxy-N,N'-di-tert-butylmaleamide,

N-hydroxy-N-tert-butylmaleamide,

N,N'-dihydroxy-N,N'-di-tert-butyloxalamide,

N,N'-dihydroxy-N,N'-di-tert-butylphosphoramide.

Compounds which are preferably selected as mediators are from the group consisting of N-hydroxy-N-methylbenzamide, N-hydroxy-N-methylbenzenesulfonamide, N-hydroxy-N-methyl-p-toluenesulfonamide, N-hydroxy-N-methylfuran-2-carboxamide, N,N'-dihydroxy-N,N'-dimethylphthalamide, N,N'-dihydroxy-N,N'-dimethylterephthalamide,

N,N'-dihydroxy-N,N'-dimethylbenzene-1,3-disulfonamide,

N-hydroxy-N-tert-butylbenzamide,

N-hydroxy-N-tert-butylbenzenesulfonamide,

N-hydroxy-N-tert-butyl-p-toluenesulfonamide,

N-hydroxy-N-tert-butylfuran-2-carboxamide,

N,N'-dihydroxy-N,N'-di-tert-butylterephthalamide, N-hydroxy-N-isopropylbenzamide, N-hydroxy-N-isopropyl-p-toluenesulfonamide, N-hydroxy-N-isopropylfuran-2-carboxamide, N,N'-dihydroxy-N,N'-diisopropylterephthalamide, N,N'-dihydroxy-N,N'-diisopropylbenzene-1,3-disulfonamide, N-hydroxy-N-methyl-acetamide, N-hydroxy-N-tert-butylacetamide, N-hydroxy-N-isopropylacetamide, N-hydroxy-N-cyclohexylacetamide, N-hydroxy-N-methylpivalamide, N-hydroxy-N-tert-butyl-acrylamide, N-hydroxy-N-isopropylacrylamide, N-hydroxy-N-methyl-3-oxobutyramide, N,N'-dihydroxy-N,N'-dibenzoylethylenediamine,

N,N'-dihydroxy-N,N'-di-tert-butylmaleamide,

N-hydroxy-N-tert-butylmaleamide,

N,N'-dihydroxy-N,N'-di-tert-butyloxalamide.

The mediator can furthermore be selected from the group of the oximes of the general formula XXIV or XXV ##STR17## and their salts, ethers or esters, where U is identical or different and is O, S or NR⁵⁵,

R⁵⁵ being hydrogen, hydroxyl, formyl, carbamoyl, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono or phosphonooxy radical, ester or salt of the phosphonooxy radical,

it being possible for carbamoyl, sulfamoyl, amino and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁵⁶ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁵⁶,

R⁵⁶ being identical or different and being hydroxyl, formyl, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, ester or salt of the sulfono radical, sulfamoyl, nitro, amino, phenyl, C₁ -C₅ -alkyl or C₁ -C₅ -alkoxy radical and

the radicals R⁵⁷ and R⁵⁸ being identical or different and being halogen, carboxyl radical, ester or salt of the carboxyl radical, or having the meanings mentioned for R⁵⁵, or being linked to a ring [--CR⁶¹ R⁶² ]_(n) where n equals 2, 3 or 4 and

R⁵⁹ and R⁶⁰ having the meanings mentioned for R⁵⁵ and R⁶¹ and R⁶² being identical or different and being halogen, carboxyl radical, ester or salt of the carboxyl radical, or having the meanings mentioned for R⁵⁵.

Especially preferred as mediators are compounds of the general formula XXIV where U is O or S and the remaining radicals have the meanings mentioned above. An example of such a compound is dimethyl 2-hydroxyiminomalonate.

Furthermore especially preferred as mediators are isonitroso derivatives of cyclic ureides of the general formula XXV. Examples of such compounds are 1-methylvioluric acid, 1,3-dimethylvioluric acid, thiovioluric acid, alloxane 4,5-dioxime.

Particularly preferred as mediator is alloxane 5-oxime hydrate (violuric acid) and/or its esters, ethers or salts.

The mediator can furthermore be selected from the group of the vicinally nitroso-substituted aromatic alcohols of the general formula XXVI or XXVII ##STR18## and their salts, ethers or esters, where R⁶³, R⁶⁴, R⁶⁵ and R⁶⁶ are identical or different and are hydrogen, halogen, hydroxyl, formyl, carbamoyl, carboxyl radical, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, cyano, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono or phosphonooxy radical, ester or salt of the phosphonooxy radical,

it being possible for carbamoyl, sulfamoyl, amino and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁶⁷ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁶⁷,

R⁶⁷ being identical or different and being hydroxyl, formyl, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, C₁ -C₅ -alkyl or C₁ -C₅ -alkoxy radical, or it being possible for the radicals R⁶³ -R⁶⁶, in pairs, to be linked to give a ring [CR⁶⁸ R⁶⁹ --]_(m), where m is an integer and denotes a value of 1 to 4, or linked to give a ring [CR⁷⁰ ═CR⁷¹ ]_(n), where n is an integer and denotes a value of 1 to 3, and

R⁶⁸, R⁶⁹, R⁷⁰ and R⁷¹ being identical or different and having the meanings mentioned for R⁶³ to R⁶⁶.

Aromatic alcohols are preferably to be understood as meaning phenols or higher-condensed phenol derivatives.

Preferred as mediators are compounds of the general formula XXVI or XXVII whose synthesis can be based on the nitrosization of substituted phenols. Examples of such compounds are 2-nitrosophenol, 3-methyl-6-nitrosophenol,

2-methyl-6-nitrosophenol, 4-methyl-6-nitrosophenol, 3-ethyl-6-nitrosophenol, 2-ethyl-6-nitrosophenol,

4-ethyl-6-nitrosophenol, 4-isopropyl-6-nitrosophenol,

4-tert-butyl-6-nitrosophenol, 2-phenyl-6-nitrosophenol,

2-benzyl-6-nitrosophenol, 4-benzyl-6-nitrosophenol,

2-hydroxy-3-nitrosobenzyl alcohol, 2-hydroxy-3-nitrosobenzoic acid, 4-hydroxy-3-nitrosobenzoic acid,

2-methoxy-6-nitrosophenol, 3,4-dimethyl-6-nitrosophenol,

2,4-dimethyl-6-nitrosophenol, 3,5-dimethyl-6-nitrosophenol, 2,5-dimethyl-6-nitrosophenol, 2-nitrosoresorcin,

4-nitrosoresorcin, 2-nitrosoorcin, 2-nitrosophloroglucine and 4-nitrosopyrogallol, 4-nitroso-3-hydroxyaniline, 4-nitro-2-nitrosophenol.

Furthermore preferred as mediators are o-nitroso derivatives of higher-condensed aromatic alcohols. Examples of such compounds are 2-nitroso-1-naphthol, 1-methyl-3-nitroso-2-naphthol and 9-hydroxy-10-nitrosophenanthrene.

Especially preferred as mediators are 1-nitroso-2-naphthol, 1-nitroso-2-naphthol-3,6-disulfonic acid, 2-nitroso-1-naphthol-4-sulfonic acid, 2,4-dinitroso-1,3-dihydroxybenzene, and esters, ethers or salts of the compounds mentioned.

The mediator can furthermore be selected from the group consisting of hydroxypyridines, aminopyridines, hydroxyquinolines, aminoquinolines, hydroxyisoquinolines, aminoisoquinolines, with the nitroso or mercapto substituents which are in the ortho- or para-positions relative to the hydroxyl or amino groups, tautomers of the compounds mentioned, and their salts, ethers and esters.

Preferred as mediators are compounds of the general formula (XXVIII), (XXIX) or (XXX) ##STR19## and tautomers, salts, ethers or esters of the compounds mentioned, where, in formulae XXVIII, XXIX and XX, two radicals R⁷² which are in the ortho- or para-position relative to each other are the hydroxyl and nitroso radical or hydroxyl and mercapto radical or nitroso radical and amino radical

and the remaining radicals R⁷² are identical or different are are selected from the group consisting of hydrogen, halogen, hydroxyl, mercapto, formyl, cyano, carbamoyl, carboxyl radical, ester and salt of the carboxyl radical, sulfono radical, ester and salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono and phosphonooxy radical, ester and salt of the phosphonooxy radical, and

it being possible for carbamoyl, sulfamoyl, amino, mercapto and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁷³,

and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁷³,

R⁷³ being identical or different and being hydroxyl, formyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy radical or C₁ -C₅ -alkylcarbonyl radical and

it being possible for in each case two radicals R⁷² or two radicals R⁷³ or R⁷² and R⁷³, in pairs, to be linked via a bridge [--CR⁷⁴ R⁷⁵ --]_(m) where m equals 1, 2, 3 or 4 and R³ and R⁴ are identical or different and are a carboxyl radical, ester or salt of the carboxyl radical, phenyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy radical or C₁ -C₅ -alkylcarbonyl radical and

it being possible for one or more nonadjacent groups [--CR⁷⁴ R⁷⁵ --] to be replaced by oxygen, sulfur or by an imino radical which is optionally substituted by C₁ -C₅ -alkyl, and it being possible for two adjacent groups [--CR⁷⁴ R⁷⁵ --] to be replaced by a group [--CR⁷⁴ ═R --].

Especially preferred as mediators are compounds of the general formula (XXVIII) or (XXIX) and their tautomers, salts, ethers or esters, where, in formulae (XXVIII) and (XXIX) especially preferred meanings of two radicals R⁷² in the ortho-position relative to each other are the hydroxyl and nitroso radical or hydroxyl and mercapto radical or nitroso radical and amino radical and the remaining radicals R⁷² are identical or different and are selected from the group consisting of hydrogen, hydroxyl, mercapto, formyl, carbamoyl, carboxyl radical, ester and salt of the carboxyl radical, sulfono radical, ester and salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₅ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono and phosphonooxy radical, ester and salt of the phosphonooxy radical,

it being possible for carbamoyl, sulfamoyl, amino, mercapto and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁷³ and

it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₅ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁷³,

R⁷³ having the meanings which have already been mentioned and

it being possible for in each case two radicals R⁷³, in pairs, to be linked via a bridge [--CR⁷⁴ R⁷⁵ --]_(m) where m equals 2, 3 or 4 and

R⁷⁴ and R⁷⁵ having the meanings which have already been mentioned and

it being possible for one or more nonadjacent groups [--CR⁷⁴ R⁷⁵ --] to be replaced by oxygen or by an imino radical which is optionally substituted by C₁ -C₅ -alkyl.

Examples of compounds which can be employed as mediators are 2,6-dihydroxy-3-nitrosopyridine, 2,3-dihydroxy-4-nitrosopyridine,

2,6-dihydroxy-3-nitrosopyridine-4-carboxylic acid,

2,4-dihydroxy-3-nitrosopyridine, 3-hydroxy-2-mercaptopyridine, 2-hydroxy-3-mercaptopyridine, 2,6-diamino-3-nitrosopyridine, 2,6-diamino-3-nitrosopyridine-4-carboxylic acid,

2-hydroxy-3-nitrosopyridine, 3-hydroxy-2-nitrosopyridine,

2-mercapto-3-nitrosopyridine, 3-mercapto-2-nitrosopyridine,

2-amino-3-nitrosopyridine, 3-amino-2-nitrosopyridine,

2,4-dihydroxy-3-nitrosoquinoline, 8-hydroxy-5-nitrosoquinoline,

2,3-dihydroxy-4-nitrosoquinoline, 3-hydroxy-4-nitrosoisoquinoline, 4-hydroxy-3-nitrosoisoquinoline, 8-hydroxy-5-nitrosoisoquinoline and tautomers of these compounds.

Preferred as mediators are 2,6-dihydroxy-3-nitrosopyridine, 2,6-diamino-3-nitrosopyridine, 2,6-dihydroxy-3-nitrosopyridine-4-carboxylic acid, 2,4-dihydroxy-3-nitrosopyridine, 2-hydroxy-3-mercaptopyridine, 2-mercapto-3-pyridinol, 2,4-dihydroxy-3-nitrosoquinoline, 8-hydroxy-5-nitrosoquinoline, 2,3-dihydroxy-4-nitrosoquinoline and tautomers of these compounds.

The mediator can furthermore be selected from the group of the stable nitroxyl radicals (nitroxides), i.e. these free radicals can be obtained, characterized and stored in pure form.

Mediators which are preferably employed in this case are compounds of the general formula (XXXI), (XXXII) or (XXXIII) ##STR20## where Ar is a monovalent homo- or heteroaromatic mono- or binuclear radical, and

it being possible for this aromatic radical to be substituted by one or more, identical or different radicals R⁷⁷ selected from the group consisting of halogen, formyl, cyano, carbamoyl, carboxyl, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono and phosphonooxy radical, ester or salt of the phosphonooxy radical, and

it being possible for phenyl, carbamoyl and sulfamoyl radicals to be unsubstituted or mono- or polysubstituted by a radical R⁷⁸, it being possible for the amino radical to be mono- or disubstituted by R⁷⁸ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁷⁸,

it being possible for R⁷⁸ to be present once or more than once, R⁷⁸ being identical or different and being hydroxyl, formyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy or C₁ -C₅ -alkylcarbonyl radical and

R⁷⁶ is identical or different and is halogen, hydroxyl, mercapto, formyl, cyano, carbamoyl, carboxyl radical, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono, phosphonooxy radical, ester or salt of the phosphonooxy radical

and, in the case of bicyclic stable nitroxyl radicals (structure XXXIII), R⁷⁶ can also be hydrogen, and

it being possible for carbamoyl, sulfamoyl, amino, mercapto and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁷⁹ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁷⁹, R⁷⁹ being identical or different and being hydroxyl, formyl, cyano, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy radical or C₁ -C₅ -alkylcarbonyl radical, and it being possible for in each case two radicals R⁷⁸ or R⁷⁹, in pairs, to be linked via a bridge [--CR⁸⁰ R⁸¹ --]_(m) where m equals 0, 1, 2, 3 or 4, and

R⁸⁰ and R⁸¹ being identical or different and being halogen, carboxyl radical, ester or salt of the carboxyl radical, carbamoyl, sulfamoyl, phenyl, benzoyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy radical or C₁ -C₅ -alkylcarbonyl radical, and it being possible for one or more nonadjacent groups [--CR⁸⁰ R⁸¹ --] to be replaced by oxygen, sulfur or by an imino radical which is optionally substituted by C₁ -C₅ -alkyl, and it being possible for two adjacent groups [--CR⁸⁰ R⁸¹ --] to be replaced by a group [--CR⁸⁰ ═CR⁸¹ --], [--CR⁸⁰ ═N--] or [--CR⁸⁰ ═N(O)--].

Especially preferred as mediators are nitroxyl radicals of the general formulae (XXXIV) and (XXXV), ##STR21## where R⁸² is identical or different and is phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl or carbonyl-C₁ -C₆ -alkyl,

it being possible for phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁸⁴ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁸⁴,

it being possible for R⁸⁴ to be present once or more than once, R⁸⁴ being identical or different and being hydroxyl, formyl, carboxyl radical, ester or salt o the carboxyl radical, carbamoyl, sulfono, sulfamoyl, nitro, nitroso, amino, phenyl, benzoyl, C₁ -C₅ -alkyl, C₁ -C₅ -alkoxy radical or C₁ -C₅ -alkylcarbonyl radical and

R⁸³ is identical or different and is hydrogen, hydroxyl, mercapto, formyl, cyano, carbamoyl, carboxyl radical, ester or salt of the carboxyl radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl, carbonyl-C₁ -C₆ -alkyl, phospho, phosphono or phosphonooxy radical, ester or salt of the phosphonooxy radical,

it being possible for carbamoyl, sulfamoyl, amino, mercapto and phenyl radicals to be unsubstituted or to be mono- or polysubstituted by a radical R⁷⁸ and it being possible for the aryl-C₁ -C₅ -alkyl, C₁ -C₁₂ -alkyl, C₁ -C₅ -alkoxy, C₁ -C₁₀ -carbonyl and carbonyl-C₁ -C₆ -alkyl radicals to be saturated or unsaturated, branched or unbranched and to be mono- or polysubstituted by a radical R⁷⁸ and it being possible for a [--CR⁸³ CR⁸³ --] group to be replaced by oxygen, an imino radical which is optionally substituted by C₁ -C₅ -alkyl, a (hydroxy)imino radical, a carbonyl function or by a vinylidene function which is optionally mono- or disubstituted by R⁷⁸ and it being possible for two adjacent groups [--CR⁸³ R⁸³ --] to be replaced by a group [--CR⁸³ ═CR⁸³ --] or [--CR ═N--] or [--CR⁸³ ═N(O)--].

Examples of compounds which can be employed as mediators are

2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO),

4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-acetamido-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-(ethoxyfluorophosphinyloxy)-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-(isothiocyanato)-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-maleimido-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-(4-nitrobenzoyloxy)-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-(phosphonooxy)-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-cyano-2,2,6,6-tetramethyl-1-piperidinyloxy,

3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-1-oxyl,

4-phenyl-2,2,5,5-tetramethyl-3-imidazolin-1-yloxy-3-oxide,

4-carbamoyl-2,2,5,5-tetramethyl-3-imidazolin-1-yl oxy-3-oxide,

4-phenacetylidene-2,2,5,5-tetramethylimidazolin-1-yloxy,

3-(aminomethyl)-2,2,5,5-tetramethyl-N-pyrrolidinyloxy,

3-carbamoyl-2,2,5,5-tetramethyl-N-pyrrolidinyloxy,

3-carboxy-2,2,5,5-tetramethyl-N-pyrrolidinyloxy,

3-cyano-2,2,5,5-tetramethyl-N-pyrrolidinyloxy,

3-maleimido-2,2,5,5-tetramethyl-N-pyrrolidinyloxy,

3-(4-nitrophenoxycarbonyl)-2,2,5,5-tetramethyl-N-pyrrolidinyloxy.

Preferred mediators are

2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO),

4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-acetamido-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-(isothiocyanato)-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-maleimido-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-(4-nitrobenzoyloxy)-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-(phosphonooxy)-2,2,6,6-tetramethyl-1-piperidinyloxy,

4-cyano-2,2,6,6-tetramethyl-1-piperidinyloxy,

3-carbamoyl-2,2,5,5-tetramethyl-1-pyrrolinidinyloxy,

4-phenyl-2,2,5-5-tetramethyl-3-imidazolin-1-yloxy-3-oxide,

4-carbamoyl-2,2,5-5-tetramethyl-3-imidazolin-1-yloxy-3-oxide,

4-phenacetylidene-2,2,5,5-tetramethyl-1-imidazolidinyloxy.

Particularly preferred as mediators are 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy.

Especially preferred mediators are selected from the group consisting of N-hydroxyphthalimide, 1-hydroxy-1H-benzotriazole, violuric acid, N-hydroxyacetanilide, nitrosonaphthols, nitrosopyridinols and their derivatives which have been given above.

Very especially preferred are

3-amino-N-hydroxyphthalimide, 4-amino-N-hydroxyphthalimide, N-hydroxyphthalimide, 3-hydroxy-N-hydroxyphthalimide, 3-methoxy-N-hydroxyphthalimide,

3,4-dimethoxy-N-hydroxyphthalimide,

4,5-dimethoxy-N-hydroxyphthalimide,

3,6-dihydroxy-N-hydroxyphthalimide,

3,6-dimethoxy-N-hydroxyphthalimide,

3-methyl-N-hydroxyphthalimide,

4-methyl-N-hydroxyphthalimide,

3,4-dimethyl-N-hydroxyphthalimide,

3,5-dimethyl-N-hydroxyphthalimide,

3,6-dimethyl-N-hydroxyphthalimide,

3-isopropyl-6-methyl-N-hydroxyphthalimide,

3-nitro-N-hydroxyphthalimide, 4-nitro-N-hydroxyphthalimide, 1-hydroxy-1H-benzotriazole, violuric acid, N-hydroxyacetanilide, 3-nitrosoquinoline-2,4-diol,

2,4-dihydroxy-3-nitrosopyridine, 2,6-dihydroxy-3-nitrosopyridine, 2,4-dinitroso-1,3-dihydroxybenzene, 2-nitroso-1-naphthol-3-sulfonic acid and 1-nitroso-2-naphthol-3,6-disulfonic acid.

The oxidation is preferably carried out in the presence of 0.01 to 10 equivalents, preferably 0.05 to 1 equivalent, especially preferably 0.1 to 0.5 equivalent of one or more of the mediators described, preferably with one or two mediators, especially preferably with one mediator in water.

If appropriate, this is done with addition of 1 to 90 percent by weight, preferably 5 to 30 percent by weight, of a solvent which is at least partially miscible with water. It is preferred to add 1 to 3 organic solvents which are miscible with water as cosolvents. Examples of organic solvents which are miscible with water are ethanol, methanol, isopropanol, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, acetone, acetonitrile, acetamide, tetrahydrofuran, dioxane, DMSO, DMF, sulfolane, methyl acetate, ethyl acetate, formic acid, acetic acid or propionic acid, or any mixtures of these.

The pH of the solution is preferably 2 to 8, especially preferably 4 to 5.

The reactions are preferably carried out at temperatures between 5 and 70° C., especially preferably 35-50° C., and the reaction times are preferably 2 to 100 hours, especially preferably 5 to 50 hours.

Oxidants which are preferably employed are air, oxygen, hydrogen peroxide, organic peroxides, peracids, perborates or persulfates, in each case in combination with enzymes or metal oxides.

The term enzyme for the purposes of the invention also includes enzymatically active proteins or peptides or prosthetic groups of enzymes. Enzymes which can be employed in the multi-component system according to the invention are oxidoreductases of classes 1.1.1 to 1.97 in accordance with the International Enzyme Nomenclature, Committee of the International Union of Biochemistry and Molecular Biology (Enzyme Nomenclature, Academic Press, Inc., 1992, pp. 24-154).

Enzymes of the classes mentioned below are preferably employed: Enzymes of class 1.1, which embrace all dehydrogenases which act on primary, secondary alcohols and semiacetals and which have, as acceptors NAD⁺ or NADP⁺ (subclass 1.1.1), cytochromes (1.1.2), oxygen (O₂) (1.1.3), disulfides (1.1.4), quinones (1.1.5) or which have other acceptors (1.1.99).

Especially preferred amongst this class are the enzymes of class 1.1.5 with quinones as the acceptors and the enzymes of class 1.1.3 with oxygen as the acceptor.

Particularly preferred amongst this class is cellobiose: quinone-1-oxidoreductase (1.1.5.1).

Furthermore preferred are enzymes of class 1.2. This enzyme class embraces those enzymes which oxidize aldehydes to the corresponding acids or oxo groups. The acceptors can be NAD⁺, NADP⁺ (1.2.1), cytochromes (1.2.2), oxygen (1.2.3), sulfides (1.2.4), iron-sulfur-proteins (1.2.5) or other acceptors (1.2.99).

Especially preferred here are the enzymes of group (1.2.3).with oxygen as the acceptor.

Furthermore preferred are enzymes of class 1.3.

In this class there are compiled enzymes which act on CH--CH groups of the donor.

The corresponding acceptors are NAD⁺, NADP⁺ (1.3.1), cytochromes (1.3.2), oxygen (1.3.3), quinones or related compounds (1.3.5), iron-sulfur-proteins (1.3.7) or other acceptors (1.3.99).

Especially preferred is bilirubin oxidase (1.3.3.5).

Again, the enzymes of class (1.3.3) with oxygen as the acceptor and (1.3.5) with quinones etc. as the acceptor are especially preferred here.

Furthermore preferred are enzymes of class 1.4, which act on CH--NH₂ groups of the donor.

The corresponding acceptors are NAD⁺, NADP⁺ (1.4.1), cytochromes (1.4.2), oxygen (1.4.3), disulfides (1.4.4), iron-sulfur-proteins (1.4.7) or other acceptors (1.4.99).

Here too, especially preferred are enzymes of class 1.4.3 with oxygen as the acceptor.

Furthermore preferred are enzymes of class 1.5, which act on CH--NH groups of the donor. The corresponding acceptors are NAD⁺, NADP⁺ (1.5.1), oxygen (1.5.3), disulfides (1.5.4), quinones (1.5.5) or other acceptors (1.5.99).

Again, especially preferred here are enzymes with oxygen (O₂) (1.5.3) and with quinones (1.5.5) as the acceptors.

Furthermore preferred are enzymes of class 1.6, which act on NADH or NADPH.

Here, the acceptors are NADP⁺ (1.6.1), hem proteins (1.6.2), disulfides (1.6.4), quinones (1.6.5), NO₂ groups (1.6.6) and a flavine (1.6.8) or some other acceptors (1.6.99).

Especially preferred here are enzymes of class 1.6.5 with quinones as the acceptors.

Furthermore preferred are enzymes of class 1.7, which act on other NO₂ compounds as donors and which have cytochromes (1.7.2), oxygen (O₂) (1.7.3), iron-sulfur-proteins (1.7.7) or others (1.7.99) as the acceptors.

Especially preferred here is class 1.7.3 with oxygen as the acceptor.

Furthermore preferred are enzymes of class 1.8, which act on sulfur groups as donors and which have NAD⁺, NADP⁺ (1.8.1), cytochromes (1.8.2), oxygen (O₂) (1.8.3), disulfides (1.8.4), quinones (1.8.5), iron-sulfur-proteins (1.8.7) or others (1.8.99) as the acceptors.

Especially preferred is class 1.8.3 with oxygen (O₂) and (1.8.5) with quinones as the acceptors.

Furthermnore preferred are enzymes of class 1.9, which act on hem groups as donors and which have oxygen (O₂) (1.9.3), NO₂ compounds (1.9.6) and others (1.9.99) as the acceptors.

Especially preferred here is group 1.9.3 with oxygen (O₂) as the acceptor (cytochrome oxidases).

Furthermore preferred are enzymes of class 1.12, which act on hydrogen as the donor.

The acceptors are NAD⁺ or NADP⁺ (1.12.1) or others (1.12.99).

Furthermore preferred are enzymes of class 1.13 and 1.14 (oxygenases).

Furthermore preferred enzymes are those of class 1.15, which act on superoxide free radicals as the acceptors.

Especially preferred here is superoxide dismutase (1.15.1.1).

Furthermore preferred are enzymes of class 1.16. NAD⁺ or NADP⁺ (1.16.1) or oxygen (O₂) (1.16.3) act as the acceptors.

Especially preferred here are enzymes of class 1.16.3.1 (ferroxidase, e.g. ceruloplasmin).

Furthermore preferred enzymes are those which belong to group 1.17 (acts on CH₂ groups, which are oxidized to --CHOH--), 1.18 (acts on reduce ferredoxin as donor), 1.19 (acts on reduced flavodoxin as donor) and 1.97 (other oxidoreductases).

Furthermore especially preferred are the enzymes of group 1.11., which act on a peroxide as the acceptor. This single subclass (1.11.1) contains the peroxidases.

Especially preferred here are cytochrome c peroxidases (1.11.1.5), catalase (1.11.1.6), peroxidase (1.11.1.7), iodide peroxidase (1.11.1.8), glutathione peroxidase (1.11.1.9), chloride peroxidase (1.11.1.10), L-ascorbate peroxidase (1.11.1.11), phospholipid hydroperoxide glutathione peroxidase (1.11.1.12), manganese peroxidase (1.12.1.13) and diarylpropane peroxidase (ligninase, lignin peroxidase) (1.11.1.14).

Very especially preferred are enzymes of class 1.10, which act on biphenols and related compounds. They catalyze the oxidation of biphenols and ascorbates. NAD⁺, NADP⁺ (1.10.1), cytochromes (1.10.2), oxygen (1.10.3) or others (1.10.99) act as the acceptors.

Amongst these, in turn, especially preferred enzymes are those of class 1.10.3 with oxygen (O₂) as the acceptor.

Preferred amongst the enzymes of his class are the enzymes catechol oxidase (tyrosinase) (1.10.3.1), L-ascorbate oxidase (1.10.3.3), o-aminophenol oxidase (1.10.3.4) and laccase (benzenediol: oxygen oxidoreductase) (1.10.3.2), the laccases (benzenediol: oxygen oxidoreductase) (1.10.3.2) being particularly preferred.

The abovementioned enzymes are commercially available or can be obtained by standard processes. Organisms which are suitable for producing the enzymes are, for example, plants, animal cells, bacteria and fungi. In principle, naturally occurring and genetically altered organisms may be enzyme producers. Equally, parts of single- or many-celled organisms are conceivable as enzyme producers, above all cell cultures.

Examples of organisms which are used for the particularly preferred enzymes, such as those from group 1.11.1, but mainly 1.10.3, and in particular for the production of laccases are fungi that cause white rot such as Pleurotus, Phlebia and Trametes.

Preferred amongst the metal oxides employed as oxidants are those with a solubility of less than 1 g/l in the reaction medium.

The following are preferred: bismuth(III) oxide, iridium(III) oxide, cerium(IV) oxide, coalt(II) oxide, cobalt(III) oxide, iron(III) oxide, manganese(IV) oxide, tin(IV) oxide, niobium(V) oxide, antimony(V) oxide, indium(III) oxide, mercury(II) oxide, lead(IV) oxide, silver(I) oxide, copper(II) oxide, palladium(II) oxide.

The following are especially preferred: lead(IV) oxide, manganese(IV) oxide, silver(I) oxide, copper(II) oxide, palladium(II) oxide.

The process according to the invention allows aromatic or heteroaromatic aldehydes and ketones to be prepared from the corresponding methyl or methylene compounds under mild reaction conditions.

The reaction is preferably carried out in water, if appropriate with addition of a cosolvent as solubilizer, and is therefore especially inexpensive.

The reaction solution is worked up in a simple manner, for example by extraction.

The mediators used can be employed catalytically. Aromatics which are substituted by electron donors react especially fast. The high selectivity is shown with reference to the oxidation of o-xylene. Here, the first methyl group is oxidized much faster, which allows o-tolyl aldehyde to be synthesized.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying examples. It should be understood, however, that this is designed for the purpose of illustration only and not as a definition of the limits of the invention.

EXAMPLE 1

22 ml of a dipotassium hydrogen phosphate/citric acid buffer solution of pH 4.5 (prepared by titrating a 0.2 M potassium dihydrogen phosphate solution with a 0.1 M citric acid solution and diluting to 1/4) were treated at 45° C. with 243 mg (1.60 mmol) of 3,4-dimethoxytoluene in 1 ml of ethanol. 0.180 mmol of a mediator (Table 1) was added with stirring. After approx. 10 minutes, the mixture was treated with 5 ml of an aqueous solution of 2 mg/ml laccase from Trametes versicolor (specific activity: approx. 18 IU/mg, defined with ABTS as substrate). After a reaction time of 22 hours with exposure to air, the reaction solution was extracted with chloroform and examined by N spectroscopy and gas chromatography. Yields of 3,4-dimethoxybenzaldehyde and 3,4-dimethoxybenzyl alcohol, see Table 1.

                  TABLE 1                                                          ______________________________________                                         Conversion of 3,4-dimethoxytoluene with laccase                                  and a variety of mediators (cosolvent: ethanol)                                                      Aldehyde Alcohol                                         Mediator (0.11 equ.) (%) (%)                                                 ______________________________________                                         1-hydroxy-1H-benzotriazole                                                                         85       14                                                  N-hydroxyphthalimide (=HPI) 9 4                                                3,6-dihydroxy-HPI 0.2 0.5                                                      3,4-dimethoxy-HPI 26 7                                                         4,5-dimethoxy-HPI 27 6                                                         3,6-dimethoxy-HPI 17 4                                                         315-dimethyl-HPI 33 7                                                          3-isopropyl-6-methyl-HPI 90 10                                                 3-methyl-HPI 81 7                                                              4-methyl-HPI 84 11                                                             3-amino-HPI 91 7                                                             ______________________________________                                    

EXAMPLE 2

195 mg (1.60 mmol) of 4-methylanisole were reacted analogously to Example 1 in the presence of 32.1 mg (0.180 mmol) of 3-amino-N-hydroxyphthalimide. After a reaction time of 22 hours, the reaction solution was extracted with chloroform and examined by NMR spectroscopy and gas chromatography. Yield 61% of 4-methoxybenzaldehyde (approx. 90%, based on conversion).

EXAMPLE 3

195 mg (1.60 mmol) of 4-methylanisole were reacted analogously to Example 1 in the presence of 24.3 mg (0.180 mmol) of 1-hydroxy-1H-benzotriazole. After a reaction time of 22 hours, the reaction solution was extracted with chloroform and examined by NMR spectroscopy. Yield 48% of 4-methoxybenzaldehyde (approx. 90%, based on conversion).

EXAMPLE 4

172 mg (1.60 mmol) of 4-toluidine were reacted analogously to Example 1 in the presence of 32.1 mg (0.180 mmol) of 3-amino-N-hydroxyphthalimide. After a reaction time of 22 hours, the reaction solution was brought to pH 8 with 2M NaOH, extracted with chloroform and examined by NMR spectroscopy. Yield 62% of 4-aminobenzaldehyde.

EXAMPLE 5

170 mg (1.60 mmol) of o-xylene were reacted analogously to Example 1 in the presence of 32.1 mg (0.180 mmol) of 3-amino-N-hydroxyphthalimide. After a reaction time of 4 hours and 18 hours, a further 32.1 mg (0.180 mmol) of 3-amino-N-hydroxyphthalimide were added in each case, and, after a total of 30 hours, the reaction solution was extracted with chloroform and examined by NMR spectroscopy. Yield 30% of 2-methylbenza ehyde and 7% of 2-methylbenzyl alcohol.

EXAMPLE 6

188 mg (1.60 mmol) of 4-tolunitrile were reacted analogously to Example 1 in the presence of 32.1 mg (0.180 mmol) of 3-amino-N-hydroxyphthalimide. After a reaction time of 22 hours, the reaction solution was extracted with chloroform and examined by NMR spectroscopy. Yield 10%.

EXAMPLE 7

212 mg (1.60 mmol) of 1,2,3,4-tetrahydronaphthalene in 1.1 ml of acetone were reacted analogously to Example 1 with 71 mg (0.53 mmol) of 1-hydroxy-1H-benzotriazole in 3 ml of acetone and 15 ml of an aqueous solution of 2 mg/ml laccase from Trametes versicolor. After a reaction time of 24 hours, the reaction solution was extracted with chloroform and examined by NMR spectroscopy. Yield 42% of 1-tetralone and 6% of 5-hydroxytetralin (approx. 90% yield of 1-tetralone based on conversion).

EXAMPLE 8

1-ethylbenzene was reacted analogously to Example 1 with 0.22 equivalent of 1-hydroxy-1H-benzotriazole and 10 ml of a solution of 2 mg/ml laccase. After a reaction time of 24 hours, the reaction solution was extracted with chloroform and examined by NMR spectroscopy. Yield 42% of acetophenone, 34% of 1-phenylethanol, 24% of unreacted acetophenone.

EXAMPLE 9

259 mg (1.60 mmol) of 6-methoxy-1,2,3,4-tetrahydronaphthalene in 1.1 ml of solvent were reacted analogously to Example 1 with a variety of mediators and laccase (see Table 2). After a reaction time of 24 hours, the reaction solution was extracted with chloroform and examined by NMR spectroscopy. Yields of 6-methoxy-1-tetralone and 6-methoxy-1-hydroxy-1,2,3,4-tetrahydronaphthalene, see Table 2.

                  TABLE 2                                                          ______________________________________                                         Oxidation of 6-methoxy-1,2,3,4-tetrahydro-                                       naphthalene to 6-methoxy-1-tetralone (HOBT: 1-hydroxy-1H-                      benzotriazole, 4-methyl-HPI: 4-methyl-N-hydroxyphthali-mide)                                       Laccase                                                    Mediator (equiv., cosolvent) (U/mmol) %1 %2                                  ______________________________________                                         HOBT (0.11, ethanol)                                                                             113        29     7                                            HOBT (0.22, ethanol) 113 52 13                                                 HOBT (0.33, ethanol) 113 60 12                                                 HOBT (0.11, ethanol) 339 51 11                                                 HOBT (0.33, ethanol) 339 95 2                                                  HOBT (0.11, ethanol).sup.a) 113.sup.a) 39 3                                    HOBT (0.11, acetone) 113 35 7                                                  HOBT (0.22, acetone).sup.b) 226.sup.b) 51.sup.c) 8                             HPI (0.22/acetone)b) 226.sup.b) 21.sup.d) 8                                    4-methyl-HPI (0.11, ethanol) 113 8 8                                           4-methyl-HPI (0.22, ethanol) 113 32 8                                          4-methyl-HPI (0.11, ethanol) 339 59 5                                          4-methyl-HPI (0.33, ethanol) 339 92 3                                          4-methyl-HPI (0.11, ethanol).sup.a) 113.sup.a' 36 4                            4-methyl-HPI (0.11, acetone) 113 31 6                                          3-amino-HPI (0.11, ethanol) 113 37 6                                           3-amino-HPI (0.22, ethanol) 113 32 10                                          3-N,N-dimethylamino-HPI                                                        (0.11, ethano1) 113 43 13                                                    ______________________________________                                          .sup.a) Addition in 3 portions, .sup.b) addition in 5 portions, .sup.c)        24% of unreacted 1,2,3,4tetrahydronaphthalene, .sup.d) *58% of unreacted       1,2,3,4tetrahydronaphthalene.                                            

EXAMPLE 10

22 ml of a dipotassium hydrogen phosphate/citric acid buffer solution of pH 4.5 (prepared by titrating a 0.2 M potassium dihydrogen phosphate solution with a 0.1 M citric acid solution and diluting to 1/4) were treated at 45° C. with 243 mg (1.60 mmol) of 3,4-dimethoxytoluene in 1 ml of ethanol. 32.1 mg (0.180 mmol) of 3-amino-N-hydroxyphthalimide were added with stirring. After approx. 10 minutes, 950 mg (3.97 mmol) of lead dioxide were added, and the mixture was stirred for 22 hours at 45° C. in a sealed flask. HPLC analysis of the reaction mixture revealed 9% of 3,4-dimethoxybenzaldehyde and 28% of 3,4-dimethoxybenzyl alcohol.

EXAMPLE 11

243 mg (1.60 mmol) of 3,4-dimethoxytoluene were reacted analogously to Example 8 with 32.1 mg (0.180 mmol) of 3-amino-N-hydroxyphthalimide and 346 mg (3.98 mmol) of manganese dioxide. HPLC analysis after a reaction time of 22 hours revealed 13% of 3,4-dimethoxybenzaldehyde and 19% of 3,4-dimethoxybenzyl alcohol.

EXAMPLE 12

Following the protocol of Potthast et al. (J. Org. Chem. 1995, 60, 4320), 13.7 mg (0.100 mmol) of 4-nitrotoluene in 0.1 ml of THF were added to a solution of 0.55 mg (0.010 mmol) of ABTS in 0.5 ml ot acetate buffer, and the stirred mixture was flushed for 1 minute with oxygen. After addition of 0.10 ml of laccase stock solution (Mercian, laccase activity 95 IU, based on the conversion of 4-hydroxymandelic acid as substrate), the reaction mixture turned deep bluish-green and was stirred for 23 hours at room temperature. The reaction mixture was subsequently again flushed for 1 minute with oxygen and the reaction was continued for 8 hours at 40° C., and this procedure was repeated twice more. Besides unreacted 4-nitrotoluene, 4-nitrobenzaldehyde was no longer detectable when examining the reaction solution by gas chromatography (detection limit approx. 0.02%).

EXAMPLE 13

Following the protocol of Potthast et al. (J. Org. Chem. 1995, 60, 4320), 15.2 mg (0.100 mmol) of 3,4-dimethoxytoluene in 0.1 ml of THF were added to a solution of 0.55 mg (0.010 mmol) of ABTS in 0.5 ml of acetate buffer, analogously to Example 8, and the stirred mixture was flushed for 1 minute with oxygen. After addition of 0.10 ml of laccase stock solution (see Example 10), the reaction mixture turned deep bluish-green and was stirred for 8 hours at room temperature. The reaction mixture was subsequently again flushed for 1 minute with oxygen and the reaction was continued for 16 hours at room temperature. me mixture was again flush with oxygen and the reaction was continued for 7 hours at 40° C. Examination of the reaction solution by gas chromatography revealed 0.3% of 3,4-dimethoxybenzaldehyde.

While several embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as defined in the appended claims. 

What is claimed is:
 1. A process for the preparation of an aldehyde selected from the group consisting of vinyl aldehyde, alkynyl aldehyde, and aryl aldehyde and a ketone selected from the group consisting of vinyl ketone, alkynyl ketone, and aryl ketone comprisingreacting a compound selected from the group consisting of vinyl methyl, alkynyl methyl, aryl methyl, vinyl methylene, alkynyl methylene, and aryl methylene with an oxidant and with the aid of a mediator in a reaction medium, wherein the mediator is selected from the group consisting of an aliphatic, heterocyclic, and aromatic NO and NOH containing compound.
 2. A process as claimed in claim 1, wherein the aldehyde and the ketone are each a compound of the formula 1, and the methyl compound and the methylene compound are each a compound of the formula 2 ##STR22## where Y¹ and Y² can be identical or different and are radicals having up to 20 C atoms and up to 6 rings and at least one of the radicals Y¹ or Y² is vinyl, alkynyl, or aryl, and Y¹ and Y² may also be part of a ring system; andwith the proviso that whenever the compound of formula 1 is an aldehyde, Y¹ or Y² is hydrogen.
 3. A process as claimed in claim 2, wherein Y¹ is the following: aromatic or a ring system having up to 6 rings and up to 20 C atoms, or an anthraquinonyl radical, it being possible for the aromatic radical Y¹ to be mono- to hexasubstituted,it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₁₂ -alkyl radical, it being possible for adjacent alkyl groups to form a 5-, 6- or 7-membered ring via a methylene group, or a linear or branched C₁ -C₁₂ -oxyalkyl or thioalkyl radical, it being possible for adjacent substituents to form a 5-, 6- or 7-membered ring via a methylene group, a H₂ N-- or a linear or branched C₁ -C₁₂ -N-alkylamino, a linear or branched C₁ -C₁₂ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₁₂ --OCO--, C₁ -C₁₂ --COO--, C₁ -C₁₂ --CO--, C₁ -C₁₂ --NHCO--, C₁ -C₁₂ --NHCONH--, (C₁ -C₁₂)₂ NCO--, C₁ -C₁₂ --CONH-- group, or a linear or branched C₁ -C₁₂ --OSO₂ --, C₁ -C₁₂ --NH--SO₂ --, or (C₁ -C₁₂)₂ N--SO₂ -- group, or a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group whose phenyl radicals can be mono- to pentasubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₁₂ -alkyl radical, it being possible for adjacent alkyl groups to form a 5-, 6- or 7-membered ring via a methylene group, or of a linear or branched C₁ -C₁₂ -oxyalkyl or thioalkyl radical, it being possible for adjacent substituents to form a 5-, 6- or 7-membered ring via a methylene group, a H₂ N-- or a linear or branched C₁ -C₁₂ --N-alkylamino, a linear or branched C₁ -C₁₂ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₁₂ --OCO--, C₁ -C₁₂ --COO--, C₁ -C₁₂ --CO--, C₁ -C₁₂ --NHCO--, C₁ -C₁₂ --NHCONH--, (C₁ -C₁₂)₂ NCO--, C₁ -C₁₂ --CONH--, or of a linear or branched C₁ -C₁₂ --OSO₂ --, C₁ -C₁₂ --NH--SO₂ -- or (C₁ -C₁₂)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group or an optionally mono- to trisubstituted vinyl radical or optionally substituted ethynyl radical, in which the substituents can be identical or different and have the meaning of hydrogen, linear, branched or cyclic C₁ -C₁₂ -alkyl radical where one or more methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₁₂ --N-alkylamine radical, or in which the vinyl group forms part of a ring or ring system, and Y² is the following: hydrogen, linear, branched or cyclic C₁ -C₁₂ -alkyl radical where one or more methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₁₂ --N-alkylamine radical, or an aromatic ring or ring system having up to 6 rings and up to 20 C atoms, or anthraquinonyl radical, or an optionally mono- to trisubstituted vinyl radical or optionally substituted ethynyl radical, in which the substituents can be identical or different and have the meaning of hydrogen, linear, branched or cyclic C₁ -C₁₂ -alkyl radical where one or more methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₁₂ --N-alkylamine radical, or in which the vinyl group forms part of a ring or ring system, it furthermore being possible for the radicals Y¹ and Y² to be linked via a methylene group or an ether group or via an amino group which is optionally substituted by a linear, branched or cyclic C₁ -C₁₂ -alkyl radical.
 4. A process as claimed in claim 2, wherein Y¹ is the following: 5-, 6- or 7-membered aromatic ring which can be fused to one or two further aromatic rings or an anthraquinonyl radical, it being possible for Y¹ to be mono- to tetrasubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₆ -alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or a linear or branched C₁ -C₆ -oxyalkyl or -thioalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, of a H₂ N--, or a linear or branched C₁ -C₆ --N-alkylamino, a linear or branched C₁ -C₃ -N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₆ --OCO--, C₁ -C₆ --COO--, C₁ -C₆ --CO--, C₁ -C₆ --NHCO--, C₁ -C₆ --NHCONH--, (C₁ -C₆)₂ NCO--, C₁ -C₆ --CONH--, or of a linear or branched C₁ -C₆ --OSO₂ --, C₁ -C₆ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group, it being possible for the phenyl radicals to be mono- to trisubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C₁ -C₆ -alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or a linear or branched C₁ -C₆ -oxyalkyl or -thioalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, of a H₂ N--, or a linear or branched C₁ -C₆ --N-alkylamino, a linear or branched C₁ -C₃ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear, branched or cyclic C₁ -C₆ --OCO--, C₁ -C₆ COO--, C₁ -C₆ CO--, C₁ -C₆ --NHCO--, C₁ -C₆ --NHCONH--, (C₁ -C₆)₂ NCO--, C₁ -C₆ --CONH--, or of a linear or branched C₁ -C₆ --OSO₂ --, C₁ -C₆ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl--CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group, or an optionally mono- to trisubstituted vinyl radical or optionally substituted ethynyl radical,it being possible for the substituents to be identical or different and to be hydrogen or linear, branched, or cyclic C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system, and Y² is the following: hydrogen or linear, branched or cyclic C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or a 5-, 6- or 7-membered aromatic ring which can be fused to one or two further aromatic rings or an anthraquinonyl radical, or an optionally mono- to trisubstituted vinyl radical, or an optionally substituted ethynyl radical, it being possible for the substituents to be identical or different and to be hydrogen or linear, branched, or cyclic C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system.
 5. A process as claimed in claim 2, wherein Y¹ is the following: phenyl, naphthyl, anthryl, phenanthryl, azulenyl, anthraquinonyl,it being possible for Y¹ to be mono- to trisubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear C₁ -C₆ -alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or of a linear C₁ -C₆ -oxyalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, a H₂ N--, or a linear C₁ -C₆ --N-alkylamino, a linear C₁ -C₃ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear C₁ -C₄ --OCO--, C₁ -C₄ --COO--, C₁ -C₄ --CO--, C₁ -C₄ --NHCO--, (C₁ -C₄)₂ NCO--, C₁ -C₄ --CONH--, C₁ -C₄ --NHCONH--, or C₁ -C₄ --OSO₂ --, C₁ -C₄ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl--CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group, it being possible for the phenyl radicals to be mono- to trisubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear C₁ -C₆ -alkyl radical, it being possible for adjacent alkyl groups to form a 5- or 6-membered ring via a methylene group, or of a linear C₁ -C₆ -oxyalkyl radical, it being possible for adjacent substituents to form a 5- or 6-membered ring via a methylene group, a H₂ N--, or a linear C₁ -C₆ --N-alkylamino, a linear C₁ -C₃ --N,N-dialkylamino group, NC--, O₂ N--, halogen, HOOC--, HO₃ S--, OHC--, H₂ N--COO--, H₂ N--CO--, H₂ N--CO--NH--, or a linear C₁ -C₄ --OCO--, C₁ -C₄ --COO--, C₁ -C₄ --CO--, C₁ -C₄ --NHCO--, (C₁ -C₄)₂ NCO--, C₁ -C₄ --CONH--, C₁ -C₄ --NHCONH--, or C₁ -C₄ --OSO₂ --, C₁ -C₄ --NH--SO₂ -- or (C₁ -C₃)₂ N--SO₂ -- group, or of a phenyl, diphenylmethyl, phenyl-CH═CH--, phenyl-N═N--, phenyl-N═CH--, phenyl-CH═N--, phenoxy, phenyl-NH--, phenyl-O--CO--, phenyl-CO--, phenyl-NHCO--, phenyl-CONH--, phenyl-NHCONH--, phenyl-OSO₂ -- or phenyl-NH--SO₂ -- group or an optionally mono- to trisubstituted vinyl radical, or optionally substituted ethynyl radical, in which the substituents can be identical or different and are hydrogen or linear C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system, and Y² is the following: hydrogen or a linear C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or is phenyl, naphthyl, anthryl, phenanthryl, azulenyl, anthraquinonyl, or an optionally mono- to trisubstituted vinyl radical, or optionally substituted ethynyl radical, in which the substituents can be identical or different and are hydrogen or linear C₁ -C₆ -alkyl radical where one or two methylene groups can be replaced individually by CHOH, CO, O, S, NH or by a linear or branched C₁ -C₆ --N-alkylamine radical, or in which the vinyl group forms part of a 5- or 6-membered ring or of a ring system, where, furthermore, the radicals Y¹ and Y² can be linked via a methylene group or an ether group or via an amino group which is optionally substituted by a methyl, ethyl, -- or iso-propyl radical, the linkage resulting in 5- or 6-membered rings.
 6. A process as claimed in claim 1,wherein the mediator is at least on compound selected from the group consisting of N-hydroxy-phthalimide, 1-hydroxy-1H-benzotriazole, violuric acid, N-hydroxyacetanilide, nitrosonaphthols, nitrosopyridinols and the derivatives thereof.
 7. A process as claimed in claim 1,wherein the mediator is at least one compound selected from the group consisting of 3-amino-N-hydroxyphthalimide, 4-amino-N-hydroxyphthalimide, N-hydroxyphthalimide, 3-hydroxy-N-hydroxyphthalimide, 3-methoxy-N-hydroxyphthalimide, 3,4-dimethoxy-N-hydroxyphthalimide, 4,5-dimethoxy-N-hydroxyphthalimide, 3,6-dihydroxy-N-hydroxyphthalimide, 3,6-dimethoxy-N-hydroxyphthalimide, 3-methyl-N-hydroxyphthalimide, 4-methyl-N-hydroxyphthalimide, 3,4-dimethyl-N-hydroxyphthalimide, 3,5-dimethyl-N-hydroxyphthalimide, 3,6-dimethyl-N-hydroxyphthalimide, 3-isopropyl-6-methyl-N-hydroxyphthalimide, 3-nitro-N-hydroxyphthalimide, 4-nitro-N-hydroxy-phthalimide, 1-hydroxy-1H-benzotriazole, violuric acid and N-hydroxyacetanilide, 3-nitrosoquinoline-2,4-diol, 2,4-dihydroxy-3-nitrosopyridine, 2,6-dihydroxy-3-nitrosopyridine, 2,4-dinitroso-1,3-dihydroxybenzene, 2-nitroso-1-naphthol-4-sulfonic acid and 1-nitroso-2-naphthol-3,6-disulfonic acid.
 8. A process as claimed in claim 1,wherein the oxidant is selected from the group consisting of air, oxygen, hydrogen peroxide, an organic peroxide, a peracid, a perborate and a persulfate with each oxidant in combination with an enzyme.
 9. A process as claimed in claim 8, wherein the oxidant is selected from the group consisting of air and oxygen in combination with laccase.
 10. A process as claimed in claim 1, wherein the oxidant is a metal oxide with a solubility of less than 1 g/l in the reaction medium.
 11. A process as claimed in claim 1, further comprisingadding a cosolvent comprising water with one to three solvents which are at least partially miscible with water. 